Kicking off our six-part series “Tyre Tech Talk” in RiDE magazines April 2014 issue, we looked a little closer at the nuts and bolts of tread pattern design and its impact on tyre grip. Continental have teamed up with our partner California Superbike School UK to help you make a more informed choice when choosing your tyres.
In general as riders we all want to fit the “stickiest” tyre for our bike, and many riders still see the tread pattern as a mainly decorative feature, or as something that just disperses water when riding in the wet. What many riders dont realise is that tread pattern design can have a huge effect on the levels of grip available, and here at Continental we have a similar pattern across a range of our motorcycle products, but we will look more specifically at how and why a little further on. As Deputy Chief Riding Coach Andy Peck of California Superbike School UK explains, tyre choice is about finding a balance between:
- Wet Grip
- Dry Grip
As Andy goes on to explain, its not possible to have the maximum amount of all three at the same time so you have to consider your needs, and find the product that is designed to meet those needs.
Starting with a race slick like the one in the ContiRaceAttack range, your tyre has the maximum amount of rubber in contact with the surface of the track. Many riders dont realise that racing slicks can be the stickiest tyres when riding in the wet provided that surface temperatures are hot enough. That is of course, until they start to aquaplane and unfortunately because the water has nowhere to escape through this starts to happen very quickly. Water also has a cooling effect on the tyre, and a slick tyre needs to be hot to grip which is why track riders use tyre warmers and warm-up laps to maximise the levels of grip available from the tyre.
The tread pattern on a motorcycle tyre isnt just used to disperse water from around the contact patch. The grooves in the tread also help to generate heat through the tyre carcass and compound which makes the tyre “stickier”. The surface of a slick tyre remains much the same shape when its rolling across the track surface, whereas a “knobblie” tyre such as the TKC 80 Twinduro features lots of rubber blocks that continue to move as the tyre rolls across a surface. The blocks generate heat as they move, and the grooves in our road tyres work in the same way. Therefore a tyre with plenty of tread grooves would be great in the wet because it would disperse more water and generate lots of heat, whilst a tyre with fewer grooves would evacuate less water and generate less heat making it less grippy in the wet.
The downside of a tread pattern covered in grooves, with a race rain tyre being a good example, is that it will wear more rapidly when used in dry conditions, so manufacturers will make significant modifications to the pattern in order to extend the life of the tyre. As great example of this is the ContiSportAttack 2 (pictured) which is used by BMW on the S1000RR. The centre of the tyre is predominantly rubber with no grooves, to give straight line traction and stability when the bike is upright. The grooves used in the central area of the tyre are usually designed to be in line with tyre rotation, and they then arc out towards the edge of the tyre at which point they are going across the tyre horizontally.
The reason for this tread pattern design is because when you’re travelling upright the main forces acting on the tyre are either driver (rear) or braking (front). As you lean the bike over into the corner, the main forces acting on the tyre are predominantly coming in from the side. Aligning the grooves across the various sections of the tyre with the forces acting upon those sections is key in helping to ensure even tyre wear.
As Andy from California Superbike School explains, they use the ContiSportAttack 2 on all their track bikes because a pure track oriented tyre such as a race slick has a very narrow operating temperature. As they are in and out of the pits all day long it is not practical to use tyre warmers to continually reheat the race oriented tyres as they cool down after each session. The design of the ContiSportAttack 2 offers them grip right from the off, it was designed to and therefore makes it ideal for their needs.
At Continental we use a similar tread pattern across a number of the products in our range. Each tyre features a modified version of this tread pattern which suits the tyres intended use. The key differences between each product come in the form of the compound, along with the amount and depth of the grooves along with other minor adjustments to the basic tread design.
For example the high performance ContiSportAttack 2 hypersport tyre for street use includes our Black Chili compound for quick warm-up, shorter braking distances and excellent grip on wet and dry roads. On the other hand the ContiRoadAttack 2 Evo is a sport touring tyre, and although it looks similar it features deep tread grooves for extended tyre life.
Andy also makes a very valid point when he says that grip is as much to do with the rider as it is to do with the tyre. At California Superbike School UK they teach riders about the relationship between the throttle and tyre grip. Everything that you as a rider do with the throttle affects how your tyres are loaded and as such it affects the size of the contact patch which is the amount of rubber thats holding your bike on the tarmac.
Dont miss out on part 2 in RiDE magazine. You can also see a review of all the information covered in the whole series as they are published via our Tyre Tech Talk section.