[fatoni]

Originally Posted by rvoll

This is a myth and is just not true. I've had a number of track experiences where the narrower tire was faster. The tire/wheel combo is one where the ONLY way to find out is to do a real world test. Adhesion is a combination of contact patch and contact pressure -- not just contact patch. Wider tires have less contact pressure. In addition, it is a function of the majority of directional forces. So for autocross, where you are exerting a lot of lateral forces, wider is generally better because of the squarer contact patch and the forces against that patch. On a road course, or on the road in general, where 95% of the travel is just forward, and not turning, the narrower tire tends to be faster because it is generally lighter and there is less drag. Have you ever seen a dragster with wide front wheels? On the other hand, if you have to put a lot of hp on the driving wheels (something that is not necessary with the Twins), then wider ON THE DRIVING WHEELS makes sense as you are putting more rubber on the road during acceleration. However, once you are at speed, those wider tires are a negative. None of this takes into account other factors like mpg where narrower tires are clearly better.

There are no simple axioms that can determine what is better. Manufacturers spend a lot of time getting balance for their cars and once you significantly deviate from that balance, you cannot be sure of the results.

Can you explain this?