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Does added tire width actually increase contact patch?

Old 09-11-2007, 10:54 PM
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Originally Posted by wanna911 View Post
Like what? The test clearly shows that the wheel diameter, tire type, Inflation PSI, and weight applied are the same. It was done to show this exact thing, so why would it be different, tire company had nothing to prove.

I think there are more factors with complex tire designs to be determined by a simple equation.
Either the sidewall height or the total circumference of the tire changed, right?
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Old 09-12-2007, 11:09 AM
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I am really amazed here.

There are a few of you that get it and most don't. The size of the contact patch is not affected by the width of the tire. It is just not. Wider tires are faster than narrow tires not due to a change in size of the contact patch, but a change in SHAPE.

A wide tires contact patch looks like this


A narrow tire's contact patch looks like this

Notice there are the the SAME number of + signs. Now a due to the way a tire grips the road that wide patch will stick better than the narrow one.

The only way to you change the size of the contact patch is by tire construction and tire pressure. The size of the patch is determined by weight of car (on that tire) and by the effective stiffness of that tire. The stiffness is determined by tire pressure, side wall height, and tire construction. Width can have an impact on tire stiffness, but this effect would also be tied in to alot of other factors. When designing a tire or an F1 car how a tire deforms under load in cornering and braking is critical area to focus on.

At our level of racing we simply buy tires and put them on. The tires we run are not designed for our cars in particular and the differences in size of the contact patch are governed by the actual tire and tire pressure more than if it is wider or narrower. I don't doubt that in a lab enviroments you and show a change in size of the contact patch when comparing tire withs, but this is really a secondary impact of how the sidewall stiffness interacts with tire pressure and the wheels.

Again wider is better due to an improve SHAPE of the contact patch. Not due to more rubber on the road.
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Old 09-12-2007, 11:56 AM
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I am really amazed that you missed the content at:

which demonstrates that the contact patch size can certainly be different,
as well as differently shaped. The original question is not whether/why
wider tires work better, but whether the contact patch is bigger. It
certainly can be. Yes, a wider contact patch is better for lateral acceleration.
A wider, bigger one is definitely so.
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