Motorcycle Tire Basics

Motorcycle Tire Basics
This is the first in a series of articles exploring motorcycle tire basics and various basic dynamic characteristics of the handling behavior of motorcycles. Overall this is a very complex subject and needs a good level of mathematics and physics to properly understand what’s happening. However, in these articles I’ll try and explain the basics with the absolute minimum of mathematics, but where this is unavoidable I’ll not go beyond simple trigonometry. For those that are unhappy with any mathematics at all, don’t worry, just skip those parts and the rest should still prove useful. I’ll try and illustrate the mechanics with many sketches and graphs. It seems incredible that just two small contact patches of rubber, can support our machines and manage to deliver large amounts of power to the road, whilst at the same time supporting cornering forces at least as much as the weight of the bike and rider. As such the tires exert perhaps the single most important influence over general handling characteristics, so it seems appropriate to study their characteristics before the other various aspects of chassis design. When Newton first expounded to the world his theories of mechanics, no doubt he had on his mind, things other than the interaction of motorcycle tires with the road surface. Never-the-less his suppositions are equally valid for this situation. In particular his third law states, “For every force there is an equal and opposite force to resist it.” or to put it another way “Action and reaction are equal and opposite.” Relating this to tire action, means that when the tire is pushing on the road then the road is pushing back equally hard on the tire. This applies equally well regardless of whether we are looking at supporting the weight of the bike or resisting cornering, braking or driving loads. What this particular law of Newton does not concern itself with, is which force is the originating one nor indeed does it matter for many purposes of analysis. However, as a guide to the understanding of some physical systems it is often useful to mentally separate the action from the reaction. The forces that occur between the ground and the tires determine so much the behaviour of our machines, but they are so often taken for granted. tires really perform such a multitude of different tasks and their apparent simplicity hides the degree of engineering sophistication that goes into their design and fabrication. Initially pneumatic tires were fitted to improve comfort and reduce loads on the wheels. Even with modern suspension systems it is still the tires that provide the first line of defence for absorbing road shocks. To explore carcass construction, tread compound and tread pattern in great detail is beyond the scope of this book. Rather we are concerned here with some basic principles and their effects on handling characteristics. Weight Support The most obvious function of the tire is to support the weight of the machine, whether upright or leaning over in a corner. However, the actual mechanism by which the air pressure and tire passes the wheel load to the road is often misunderstood. Consider fig. 1, this sketch represents a slice through the bottom of a rim and tire of unit thickness with an inflation pressure of P. The left hand side shows the wheel unloaded and the right hand side shows it supporting the weight F. When loaded the tire is compressed vertically and the width increases as shown, perhaps surprisingly the internal air pressure does not change significantly with load, the internal volume is little changed. At the widest section (X1) of the unloaded tire the internal half width is W1, and so the force normal to this section due to the internal pressure is simply 2.P.W1 . This force acts upwards towards the wheel rim, but as the pressure and tire width are evenly distributed around the circumference the overall effect is completely balanced. This force also has to be resisted by an equal tension (T) in the tire carcass. The loaded tire has a half width of W2 at it’s widest section (X2) and so the normal force is 2.P.W2 . Therefore, the extra force over this section, when loaded, is 2.P.(W2 ” W1) but as the tire is only widened over a small portion of the bottom part of the circumference, this force supports the load F. The above describes how the inflation pressure and tire width increase produce forces to oppose the vertical wheel loading, but does not completely explain the detail of the mechanism by which these forces are transferred to the rim. The bead of a fitted tire is an interference fit over the bead seat of the wheel rim, which puts this area into compression, the in-line component of the side-wall tension due to the inflation pressure reduces this compression somewhat. This component is shown as F1 on the unloaded half of F1 = T.cos(U1). The greater angle U2 of the side-wall when loaded means that the in-line component of the tension is reduced, thereby also restoring some of the rim to tire bead compression. This only happens in the lower part of the tire circumference, where the widening takes place. So there is a nett increase in the compressive force on the lower rim acting upward, this supports the bike weight. The nett force is the difference between the unloaded and loaded in-line forces, F = T.(cos( U1) -cos(U2)) The left hand side shows half of an inflated but unloaded tire, a tension (T) is created in the carcass by the internal pressure. To the right, the compressed and widened shape of the loaded tire is shown. The in-line components (F1 & F2) of the side-wall tension are reduced by factors equal to the cosines of the angles of the side-wall. This reduction is greater with the loaded tire resulting in a greater compressive force on the lower part of the rim. This is the principle but not the only mechanism which passes force from the wheel to the ground, the above ignores the effects of the flexure stiffness of the carcass itself, in addition to supporting the tension forces as outlined, the side-walls also have some bending resistance which can resist small wheel loads without any internal air pressure. Suspension Action In performing this function the pneumatic tire is the first object that feels any road shocks and so acts as the most important element in the machine’s suspension system. To the extent that, whilst uncomfortable, it would be quite feasible to ride a bike around the roads, at reasonable speeds with no other form of bump absorption. In fact rear suspension was not at all common until the 1940s or 50s. Whereas, regardless of the sophistication of the conventional suspension system, it would be quite impractical to use wheels without pneumatic tires, or some other form of tire that allowed considerable bump deflection. The loads fed into the wheels without such tires would be enormous at all but slow speeds, and continual wheel failure would be the norm. A few figures will illustrate what I mean:–Assume that a bike, with a normal size front wheel, hits a 25 mm, sharp edged bump at 190 km/h. This not a large bump. With no tire the wheel would then be subject to an average vertical acceleration of approximately 1000 G. (the peak value would be higher than this). This means than if the wheel and brake assembly had a mass of 25 kg. then the average point load on the rim would be 245 kN. or about 25 tons. What wheel could stand that? If the wheel was shod with a normal tire, then this would have at ground level, a spring rate, to a sharp edge, of approx. 17-35 N/mm. The maximum force then transmitted to the wheel for a 25 mm. step would be about 425-875 N. i.e. less than four thousandths of the previous figure, and this load would be more evenly spread around the rim. Without the tire the shock loads passed back to the sprung part of the bike would be much higher too. The vertical wheel velocity would be very much greater, and so the bump damping forces, which depend on wheel velocity, would be tremendous. These high forces would be transmitted directly back to bike and rider. The following five charts show some results of a computer simulation of accelerations and displacements on a typical road motorcycle, and illustrate the tire’s significance to comfort and road holding. The bike is traveling at 100 km/h. and the front wheel hits a 0.025 metre high step at 0.1 seconds. Note that the time scales vary from graph to graph. Three cases are considered: With typical vertical tire stiffness and typical suspension springing and damping. With identical tire properties but with a suspension spring rate of 100 X that of the previous. With tire stiffness 100 X the above and with normal suspension springing. So basically we are considering a typical case, another case with almost no suspension springing and the final case is with a virtually rigid tire. Structural loading, comfort and roadholding would all be adversely affected without the initial cushioning of the tire. Note that the above charts are not all to the same time scale, this is simply to better illustrate the appropriate points. This shows the vertical displacement of the front wheel. There is little difference between the maximum displacements for the two cases with a normal tire, for a small step the front tire absorbs most of the shock. However, in the case of a very stiff tire, the wheel movement is increased by a factor of about 10 times. It is obvious that the tire leaves the ground in this case and the landing bounces can be seen after 0.5 seconds. These curves show the vertical movement of the C of G of the bike and rider. As in Fig 1 it is clear that the stiff tire causes much higher bike movements, to the obvious detriment of comfort. Demonstrating the different accelerations transmitted to the bike and rider, these curves show the vertical accelerations at the C of G. Both of the stiffer tire or stiffer suspension cases show similar values of about 5 or 6 times that of the normal case, but the shape of the two curves is quite different. With the stiff suspension there is little damping and we can see that it takes a few cycles to settle down. The second bump at around 0.155 seconds is when the rear wheel hits the step, this rear wheel response is not shown on the other graphs for clarity. Front wheel vertical acceleration for the two cases with a normal tire. The early part is similar for the two cases, the suspension has little effect here, it is tire deflection that is the most important for this height of step. As in Fig 5 the lack of suspension damping allows the tire to bounce for a few cycles before settling down. As in these curves are of the wheel acceleration, the values of the normal case are overwhelmed by the stiff tire case, with a peak value of close to 600 G compared with nearly 80 G normally. Again note the effects of the landing bounces after 0.5 seconds. This high acceleration would cause very high structural loading. As the tire is so good at removing most of the road shocks, right at the point of application, perhaps it would be worth while to consider designing it to absorb even more and eliminate the need for other suspension. Unfortunately we would run into other problems. We have all seen large construction machinery bouncing down the road on their balloon tires, sometimes this gets so violent that the wheels actually leave the ground. A pneumatic tire acts just like an air spring, and the rubber acts as a damper when it flexes, but when the tire is made bigger the springing effect overwhelms the damping and we then get the uncontrolled bouncing. So there are practical restraints to the amount of cushioning that can be built into a tire for any given application. Effects of Tire Pressure Obviously, the springing characteristics mentioned above are largely affected by the tire inflation pressure, but there are other influences also. Carcass material and construction and the properties and tread pattern of the outer layer of rubber all have an effect on both the springing properties and the area in contact with the ground (contact patch). Under and over inflation both allow the tire to assume non-optimum cross-sectional shapes, additionally the inflation pressure exerts an influence over the lateral flexibility of a tire and this is a property of the utmost importance to motorcycle stability. Manufacturers’ recommendations should always be adhered to. The influence of tire pressure on the vertical stiffness of an inflated tire, when loaded on a flat surface. These curves are from actual measured data. Note that the spring rate is close to linear over the full range of loading and varies from 14 kgf/mm. at 1.9 bar pressure to 19 kgf/mm. at 2.9 bar. The effective spring rate when the tire is loaded against a sharp edge, such as a brick, is considerably lower than this, and is more non-linear due to the changing shape of the contact area as the tire “wraps” around the object. This spring rate acts in series with the suspension springs and is an important part of the overall suspension system. An interesting property of rubber is that when compressed and released it doesn’t usually return exactly to it’s original position, this is known as hysteresis. This effect is shown only for the 1.9 bar. case, the curve drawn during the loading phase is not followed during the unloading phase. The area between these two curves represents a loss of energy which results in tire heating and also acts as a form of suspension damping. In this particular case the energy lost over one loading and unloading cycle is approximately 10% of the total stored energy in the compressed tire, and is a significant parameter controlling tire bounce. Vertical stiffness of a standard road tire against a flat surface at different inflation pressures. This data is from an Avon Azaro Sport II 170/60 ZR17. The upward arrows indicate the compression of the tire and the 2nd line with the downward arrow (shown only at 1.9 bar for clarity) shows the behaviour of the tire when the load is released. The shaded area between the two lines represents a loss of energy called hysteresis. This acts as a source of suspension damping and also heats the tire. (From data supplied by Avon tires.) The lateral stiffness of the same tire measured at two different pressures. In both cases the tire was loaded vertically with it’s maximum rated capacity of 355 kgf. The lateral spring rate is less than half that of the vertical rate at 7.7 and 7.3 kgf/mm. at 2.9 and 2.5 bar respectively. It is interesting to note that at the higher pressure the tire saturates or loses adhesion at the lower figure of 460 kgf. compared to 490 kgf. at the lower pressure. Saturation is indicated when the curve more or less becomes horizontal, this is when the tire cannot support an more lateral force and it displaces or slides sideways, with an approximately constant force. The contact patch area and pressure produced at the lower air pressure has allowed more static grip. However, these tests are done with the artificial case of an upright and non-rotating wheel and hence it would be risky to extrapolate this grip characteristic to a moving machine. Although not shown, the lateral deformation would also be subject to some hysteresis and this damping and the lateral flexibility exert an important influence over the weave stability. Lateral stiffness of the same tire shown in fig. 9. The vertical load was constant at 355 kgf. and the wheel was kept vertical. As expected the tire is somewhat stiffer with the higher inflation pressure but loses grip or saturates at the lower lateral load of 460 kgf. compared to 490 kgf. at the lower pressure. (From data supplied by Avon tires.) Contact Area The tire must ultimately give it’s support to the bike through a small area of rubber in contact with the ground, and so “contact patch area = vertical force average contact patch surface pressure”. This applies under ALL conditions. The contact patch surface pressure is NOT however, the same as the inflation pressure, as is sometimes claimed. They are related but there are at least four factors which modify the relationship. Carcass stiffness, carcass shape, surface rubber depth and softness, and road surface compliance. If we have an extremely high carcass stiffness then inflation pressure will have a reduced influence. Let’s look at this in a little more detail and see why: If a tire was made just like an inner tube, that is from quite thin rubber and with little stiffness unless inflated, then the internal air pressure would be the only means to support the bike’s weight. In this case the contact patch pressure would be equal to that of the internal air pressure. For an air pressure of 2 bar and a vertical load of 1.0 kN. Then the contact area would be 5003 sq.mm. If we now increased the air pressure to say 3 bar the area would fall to 3335 sq.mm. Let’s now imagine that we substitute a rigid steel tubular hoop for our rim and tire, the area in contact with the ground will be quite small. If we now inflate the hoop with some air pressure, it doesn’t take much imagination to see that, unlike the inner tube, this internal pressure will have a negligible effect on the external area of contact. Obviously, a tire is not exactly like the steel hoop, nor the inner tube, but this does show that the carcass rigidity can reduce the contact surface area as calculated purely from inflation pressure alone. On the other hand, let’s now imagine that we cover the previous steel hoop with a layer of thick soft rubber. Now, the actual contact area will be considerably increased and the average contact patch pressure will be reduced. Substitute this mental picture back to a real tire and we see that the tread layer of rubber will give us a greater contact area and lower contact pressure than that of the inflation pressure alone. It is this compliance of the surface rubber that gives us more contact with the road when we increase tire width and diameter, but this must be balanced against the opposing effects of the carcass stiffness. Radial and bias or cross ply tires exhibit quite different characteristics in this regard. The properties of the road surface are also important, a soft surface, mud and sand for example, will obviously give support over a wider area of the tire and so reduce the contact pressure. On a hot day with softened tarmac, even a normal road will deflect significantly enough to affect the contact patch. To get a feeling for the degree of departure of the contact patch pressure from the inflation pressure, consider a completely flat tire, in this case the rubber area will probably be no more than 3 or 4 times, at most, the area when inflated correctly. Based on the notion that rubber pressure = inflation pressure, we would expect the rubber area to be much higher, infinite in fact. Another extreme case to consider: Imagine a knobbly tire with very few knobs such that only one knob supports the bike. In this example the rubber pressure is simply the weight divided by the area of the one knob, this is regardless of the inflation pressure. These are extreme examples of course but should still demonstrate the lie in the proposition that rubber contact pressure = inflation pressure. The following describes some simple measurements that I made to check out the actual relationship between load, inflation pressure and contact area. I did 2 sets of tests. For the first I kept the tire inflation pressure constant at 2.4 bar and varied the tire load between 178 and 1210 N. (allowing for the weight of the glass and wooden beams). Secondly, I keep a constant load of 1210 N. and tried varying the inflation pressure between 2.4 to 1 bar. Even with a generous allowance for experimental error the effects are clear. The graphs show that the results appeared to fit reasonably well to a smooth line, there wasn’t much scatter. Point (1) on the curve with constant inflation pressure, shows how the actual contact patch pressure is lower (just over half) than the inflation pressure, or in other words the contact area is greater. This is due to the rubber surface compliance, thus this is more important at low vertical loads, whereas carcass stiffness became more important as the load rose as shown by points (3) to (6) where the actual contact pressure is higher than the air pressure, i.e. reduced area of contact. Measurement setup. Various weights were placed on the end of a beam, which also loaded the tire via a thick plate of glass. The beam was arranged to apply the load to the tire with a 4:1 leverage. So a 25 kgf. weight would load the tire with 100 kgf. By tracing over the glass the contact area was determined. Tracings of tire footprint for different loads and pressures. The numbers relate to the data points below. The top plot shows the measured contact patch pressure at various wheel loads for a constant inflation pressure of 2.4 bar. The lower curves show the contact pressure at various inflation pressures for a fixed load of 1210 N. The numbers at the data points correspond with the contact area tracings in the previous sketch. The plain line on each plot shows the case of the contact patch pressure being equal to the inflation pressure. The carcass stiffness helps to support the machine as the air pressure is reduced, the contact patch pressure being considerably higher than the inflation pressure. It looks as though the two lines will cross at an air pressure of about 3.5 bar. (although this was not tested by measurement), at which point the surface rubber compression will assume the greatest importance. This is as per the steel hoop analogy above. We can easily see the two separate effects of surface compliance and carcass stiffness and how the relative importance of these varies with load and/or inflation pressure. These tests were only done with one particular tire, other types will show different detail results but the overall effects should follow a similar pattern. Area Under Cornering Does cornering affect tire contact area? Let’s assume a horizontal surface and lateral acceleration of 1G. Under these conditions the bike/rider CoG will be on a line at 45 to the horizontal and passing through the contact patch. There will a resultant force acting along this line through the contact patch of 1.4 times the supported weight. This force is the resultant of the supported weight and the cornering force, which have the same magnitude, in this example of a 45 lean. The force normal to the surface is simply that due to the supported weight and does NOT vary with cornering force. The cornering force is reacted by the horizontal frictional force generated by the tire/road surface and this frictional force is “allowed” by virtue of the normal force. Therefore, to a first approximation cornering force will NOT affect the tire contact area, and in fact this case could be approximated to, if we were just considering the inner tube without a real world tire. However in reality, the lateral force will cause some additional tire distortion to take place at the road/tire interface and depending on the tire characteristics, mentioned above, the contact area may well change. Another aspect to this is of course the tire cross-sectional profile. The old Dunlop triangular racing tire, for example, was designed to put more rubber on the road when leant over, so even without tire distortion the contact patch area increased, simply by virtue of the lean angle. Next month we’ll look at other aspects of tires, such as friction, grip, drifting, under- and over-steer, and tire construction and materials. by Tony Foale http://www.CarsNet.com/motorcycle

Ray Taylor is the owner of the real world San Diego Car & Cycle - Show & Swap. He also owns www.CarsNet.com and www.SanDiegoAutoSwap.com

A Look At Some Of The Different Motorcycle Engines
Motorcycles have been around for more than ten decades. During this time, motorcycle engines have developed through tweaking and reworking items to get the best performance. There have been more than

What to look for when Buying a Motorcycle Helmet.

What to look for when Buying a Motorcycle Helmet.

Buying a motorcycle helmet can be quite confusing these days. there are so many helmets to choose from, trying to figure out which one is the right one for you can take some time. Motorcycle helmets come in a variety of shapes sizes and colors. There are also quite a few manufacturers to choose from. Most people pick a helmet that fits their personality or the colors of their bike. That is a good way to it. You should like the helmet so you will wear it whenever you are out there shredding some curves. Here are a few of the most popular motorcycle helmet makers around: Icon, AGV, Suomy, ZR, Nolan, Thor and Scorpion are just a few of the popular manufacturers you can choose from. You have several types of motorcycle helmets to choose from. 

Lets talk about half helmets. These are helmets that do not cover your entire face they just cover the top of your heads the side of your head and sometimes come with a visor. A lot of these types also come with a face shield to keep debris and bugs out of your face. If the half helmet you pick does not you will need to get you some goggles. Half helmets are very popular with the cruiser crowd. Also skullcaps are popular with this crowd. A skull cap is exactly what it implies it is a helmet that only covers the cap of your skull. A skull cap usually has no visor. They are very popular with the American bike crowd mainly because the skullcaps are usually adorned with a nice paint job like skulls or an old airplane motif, bullet holes, flames, iron crosses and the like. Skullcaps are mostly for show and really do not offer much in the way of protection. You will find most of the really cool ones are not DOT and SNELL approved. So if you are looking for protection I would recommend at least a half face if not a full face helmet. For cruiser riders it is sometimes hard to ride around with a full face when your buddies are wearing next to nothing. So I would recommend at leas a half helmet if nothing else. If you absolutely want a skull cap then ck to see if you can find one that is at lest DOT approved if not DOT and Snell both. I ride a cruiser myself so I understand the notion of the wind in your hair and the freedom of the road. Its just a good idea to cover your head with some thing just in case.

Full face motorcycle helmets are mostly worn by guys that ride crotch rockets or sport bikes is the more correct term. Sport bikes these days pump out a serious amount of horsepower, therefore it is vital to wear a helmet that can protect you in case of a crash, while still keeping you comfortable when you are out there tearing up the street or track. It is almost impossible not to find a full face helmet that fits your personality or your ride. These days you can even get custom graphics painted on your helmet. Most offer a venting system which will keep air flowing in, a quick switch face shield so you can switch from a clear to a tinted shield in no time. Full face helmets are usually available starting at about $100 on up in to the $600+ range depending on what you want, but for a couple of hundred you should be able to find one that suits you. Make sure that the fit is tight enough where the helmet can not be turned when its on your head. the fit should be snug. 

Motocross helmets are the other type that we should mention. Specifically designed for off road use these helmets are made to be full face helmets with a visor and no face shield. A set of goggles is needed for them if you want eye protection. Thor makes some really nice ones for you to choose from.

When it comes to choosing a motorcycle helmet just remember a few things. Choose a helmet that you will like and will choose to wear. Make sure its DOT and Snell approved for your safety. Make sure that the helmet fits properly on your head and is comfortable enough to wear for hours on end.

By: Dominik Hussl&nbsp;&nbsp; Motorcycle enthusiast and webmaster of <b><a href="http://www.discount-motorcycle-parts.net">discount-motorcycle-parts.net</a></b>

Personal scooters are not just for fun
Personal scooters are a highly valuable mobility tool for those who, for health reasons, are unable to move around in public or in their own homes. They can ease the burden of having to carry things like heavy groceries or other personal effects. In this sense they can also help people who have back problems and strains. Progresses in technology have made scooters more energy efficient, faster, lighter and more reliable, which means that there are plenty of attractive options available to you should you ever need to purchase one. For those with a disability, scooters are an essential transportation device. One of the best things is that, if you are eligible, Medicare can cover some or all of the cost for a personal scooter. To be eligible, however you should meet the following guidelines: 1.You need a scooter to move around your home. 2.You are unable to operate a manual wheelchair. 3.Your doctor prescribes a scooter for your personal use. Please contact your Doctor and ask if you are eligible to receive government aid for a personal scooter. There is now a huge diversity of scooters available worldwide. You will first need to decide which type of scooter best fits your needs and your budget. Perhaps the most important factor when deciding to buy a new scooter is to make sure it is comfortable. You will be using it a lot and it is best to make sure you are comfortable in your new little vehicle. Not all scooters are created equal and it is important to find one which suits your body type and sense of style. Scooters come in all shapes, sizes, weights, and colors. Some scooters are even ultra light-weight so conveniently they are able to fold up into small packages meaning they can be carried virtually anywhere. This feature is great for people who have difficulty getting around generally but still have enough mobility to get around on public transport. Most carry-on scooter units are fairly easy to carry and some even weigh under 50 lbs. If you are looking for this type of scooter, make sure you are able to carry it around with you. Scooters designed specifically for the elderly are now more and more common and they are a great solution for people who have trouble moving around the house. Scooters are a good solution in many circumstances as they are able to be driven around without having to rely on someone else to power them. Think about how inconvenient it is sometimes for people in non motorized wheelchairs to have to rely on a pusher at times. Scooters are convenient and highly personal. Accessories can also enhance a scooter. Rear view mirrors, extra batteries, extra pouches, and headlights can all be purchased for your scooter. You can almost add anything you need - it just depends on your personal scooter requirements.

Darren Safrin is the owner of AtoZ <a href="http://www.atozscooters.com">Scooters</a> which is a premier source of information about Scooters. For more information, go to: http://atozscooters.com

Manufacturers driving the latest tyre technologies

The amount of advanced technology that goes into today’s premium branded car tyres is often not appreciated. Tyres, after all, are usually a distress purchase and to most consumers are simply “black and round”.

Tyre technology, however is continuously evolving, driven to a high degree by the technical demands of the vehicle manufacturers but also, to a degree, by the requirements of an increasingly demanding aftermarket.

Tyre performance can be affected by three things - by changes to the tyre structure, by altering the tread pattern and by varying the rubber compounds used in the tyre, particularly in the tread. It is not surprising to see that the leading tyre manufacturers have a variety of proprietary technologies covering all these areas.

Take Bridgestone for example. Currently, the world’s largest tyre manufacturer lists 14 key technologies covering, casing, tread pattern design and compounding. Some of these, such as the use of unidirectional tread patterns, silica compounds and rim guards to protect against kerbing damage are commonplace but some are unique to Bridgestone. Examples of the kind of technologies highlighted by Bridgestone are:

Diamond Bead - A new construction method for the bead coil, which increases the torsional stiffness of the bead coil to create a more uniform contact patch and therefore improved handling.

Flat Force Block - A new tread block design, which varies the angle of the block edges in accordance with their size. This provides a more uniform contact pressure and therefore a smoother ride.

Key Hole Sipes - These narrow slots in the tread increase in width as the tyre wears helping the tyre to maintain performance as it gets older.

Multicell Compound - An advanced and unique foam rubber based compound, the high porosity of which anables water absorption and an increased “edge-effect” to improve grip on ice.

Riblet - These are circumferential micro-grooves located on the surface of multicell compound tyres. These aborb a film of water on icy surfaces for improved grip when the tyres are new and before the multicell pores become visible.

If tyre manufacturers are continuing to evolve their tyre technology with a view to gaining a competitive advantage over their rivals, there are certain areas of technology, which are coming in for particular attention. One of these is undoubtedly the area of run-flat tyres and the associated area of tyre pressure monitoring systems. The leading manufacturers differ to some degree in the tyre technology they are using for their run-flat systems.

Michelin’s PAX system, for example incorporates a special wheel with an asymmetric profile, which allows a support ring to be inserted, which bears the vehicle’s load and allows it to be steered at zero pressure.

However, their Michelin ZP system functions by means of more robust sidewalls, reinforced with a special rubber compound to carry the vehicle weight. An innovative bead area, delps the deflated tyre stay on the rim.

A further example of the use of compounding to obtain a stiffer sidewall is Goodyear’s Run-On Flat system. This system incorporates reinforced sidewall inserts using Goodyear’s own compounding technology in order to create higher sidewall striffness. In addition, rim guards and tensioning devices on the outside of the sidewall are used to help maintain tension in the case of a flat.

Continental, like Michelin has two systems. The ContiSupportRing is a metal ring on a flexible support directly mounted on the rim, whereas the company’s SSR self-supporting run-flat tyre incorporates a special rubber reinforcement in the sidewall, which takes the vehicle weight after pressure has been lost.

Bridgestone has also taken the support ring route with its Bridgestone Support Ring system.

So where next for tyres? We wait with interest to see how the tyre manufacturers can further innovate their products and keep improving tyre technology.

About Author : Article produced by <a href="http://www.BlackCircles.com">BlackCircles.com</a> - discount <a href="http://www.blackcircles.com/">tyres</a> for cars, 4×4s, and motorbikes in the UK. Tyres can be ordered online and fitted at your local garage.

When Buying Motorcycle Boots Safety Takes First Place Over Fashion
Today bikers are trend setters. Gone are the days when their typical trademark was their big black boots, leather gloves and heavy chains and rings. But now they are very stylish and prefer to dress i

Why I Like Classic Car & Cycle People!
While watching the TV news, I was appalled at how many people can’t just get along, to quote Rodney King. It is truly a very sad situation. Then I thought about all the different types of people we have at our event and how well they all get along. In the 18 years we have been doing our events, we have never had any trouble with the participants at our shows. Bikers, Low Riders, Classic Cars, Hot Rodders, Sports Cars types and Tuner owners, they all attend our classic car & cycle show and all of them have a great time. Don’t get me wrong, they all have different likes and dislikes, but they are tolerant of their fellow gear heads. The world could learn a lot from Gear Heads! Learn to appreciate the other person’s point of view. Low Riders always draw a crowd when they put their vehicles through their “dance”. Now I’m not at all interested in having a car that hops, but I sure can appreciate the work and engineering that goes into allowing thousands of pounds of Chevy to bounce six feet off the ground. I also don’t want a car with 1000 horsepower with a blower sticking out of the hood. but I sure do enjoy checking out those types of cars at the car shows. The way I see it, we are all different and we should revel in these differences not curse them. Diversity makes the world an interesting and fun place to live in. It’s a shame that some people feel its either their way or the highway. Whether its religion, politics or drive trains, we all need to love our neighbors and that which makes them unique. If the world was made of Classic Car and Cycle People, what a wonderful place it would be! See Ya There! Ray Taylor Owner of the San Diego Auto Swap and the Classic Cars Net Free Classifieds http://www.CarsNet.com http://www.SanDiegoAutoSwap.com

Ray Taylor is the owner of the real world San Diego Car & Cycle - Show & Swap. He also owns www.CarsNet.com, www.SanDiegoAutoSwap.com

History of Gas Scooters

The first patents for scooters go back as far as 1921. The Razor scooter was later developed by Gino Tsai in Shanghai, Taiwan and became an instant hit with the public. It didn’t take long for motor scooter popularity to expand all over the globe.

Even before 1950 there were as many as 110,000 scooters on the road in Italy alone. It has been just a little over 50 years since the Vespa-Douglas Corporation in the UK sold their first gas scooters. The Douglas corporation was on the verge of bankruptcy when they first began selling their gas scooters. It was a big hit at the 1950 Motorcycle Show and saved the company from possible financial ruin.

From 1950 to 1958 Vespa sold over 125,000 of their gas powered scooters in the UK. Why the great success? During this period the European countries didn’t have a great deal of money and there was not much gas available to the public. Due to the scarcity of gasoline and the high gas mileage of the gas motor scooter it’s popularity quickly escalated.

It didn’t take long for the Italian models (the Piaggio from Vespa and the Lambretta from Innocenti) to branch out to other countries. In France they became so popular the French tried to get in on the boom by manufacturing their own. By the early to mid 1950s the sale of gas scooters climbed to about 1 million a year in France alone.

Other countries wanted to profit from the newest craze and tried to climb on the band wagon. While some were successful others were not. Germany began to manufacture larger touring models, but this did not satisfy the public in the way the smaller, cheaper and more fuel-efficient models from Italy and France did. These smaller models were extremely popular in the European market.

Tourist Scooters Manufacturers in Germany built some very strong and powerful versions and were the first to install electric starters. These larger versions were great for traveling, touring and even racing, but were not as popular as the smaller, cheaper, more efficient models used for traveling shorter distances around town.

Vespa began marketing a couple of very popular gas powered scooters from Piaggio, the GS 125cc and the GS 150cc. These were improved versions of the earlier models for several reasons. The biggest reason is probably because the heavy gear mechanism rods were replaced by smaller and lighter cables.

France’s Roussey Scooters tried to one-up the Italian competition by coming out with a 175cc model. These were very nice vehicles and included the first water-cooled engines along with other new features, but because it had a pull-start it could not compete with the newer models from Italy that were already offering versions with electric starts.

As these wonderful vehicles have evolved over the years they have become increasingly more popular all over the world. Today they are everywhere. They are cheap to purchase, economical to operate, and are very handy and functional. These are not toys and are genuinely a lot of fun to ride. There are electric, gas powered, foldable, mobility and utility scooters.

The electric types are often used by kids and teens, but are also popular with the elderly and handicapped. Models for the handicapped are usually called mobility scooters. Folding varieties can be folded up and conveniently stored under desks, in closets or in other tiny areas and utility types are used for many different purposes. They are more popular than go karts, mini bikes or go carts. Scooters, sometimes called mopeds or go peds, are very functional, convenient and are here to stay.

J Larry Alan is a freelance author providing information about a variety of scooter topics including <a href="http://www.my-gas-scooters.com">gas scooters</a>, <a href="http://www.my-gas-scooters.com/gaspoweredscooters.html">gas powered scooters</a> and <a href="http://www.my-gas-scooters.com/gasmotorscooters.html">motor scooters</a>.