I have a question about a tires contact patch.

If you have two tires... both tires have a width of say 10'' ,but one tire is 11'' tall, the other tire is 18''tall. Would there be any difference in contact patch?

 

no..just number of revolutions

 

The 18" tall tire would have a slightly larger contact area because of the diameter being larger. Don't believe me? say one tire is 11" tall and the other is 18' tall. The contact difference between these would be noticable.

 

A good way to think of it would be to carry it to the extreme-say a one mile high tire and a one inch high tire.
The mile high tire patch would be a block long and the one inch tire would be about 1/16 of an inch.
Roy

 

Actually, this would not be true if both tires/wheels weighed the same.

Let's assume that you have a perfectly balanced car that weighs 3200lbs. and the tire patch is 10" wide all the way around and they are inflated to 32psi. At that tire pressure you will require 100sq. inches of contact patch to support the car, or 25sq.in. per tire or 10" wide would require the tire to flatten so that you had 2.5" x 10" on the ground.

Now if your tire is 12.5" wide and still inflated to 32psi. it would only have to flatten so that you had 2" x 12.5" to support the car. Likewise, a 6.25" wide tire would flatten to a 4" long patch.

Now getting back to the original question, theoretically there would be no difference in the contact patch between an 18" tall tire and an 11" tall tire, or a mile high tire if they weigh the same. The difference would come in as the percentage of weight saved/lossed on the entire vehicle.

Of course as with all such theoretical calculations, all the variables and unknown parameters must be taken into consideration. So in fact there would probably be some minor differences. One such variable that I can think of off the top of my head might be the difference in pressure over the entire contact patch due to the deformation of the original shape of the tire for example.

I hope that makes sense.

 

 

Why don't you explain it to us LeMans?

 

It's been explained pretty well, but I'm wondering what the question pertains to?

Dope

 

http://www.exploratorium.edu/snacks/...ght/index.html

As long as the differently sized tires are inflated to the same pressure, there's really no difference in contact patch size.

 

Well ...The question pertains to (you guys are gonna love this).

I went out the other day and drove a racing go-Kart (shifter kart).

I was stunned by the lateral grip I was told up to 1.7 lateral G's(it felt like it.

The tires they were running are 7x11 or 11x7 I forget exactly ,But considerably shorter than our corvette rims 17'' 18''.

Given that the go-karts tires were almost as wide as say the Corvettes tires .I wondered if the corvette would have a bigger contact patch given the taller tire ..of course widths being the same( and any other factors other than width and height).

Thats where this question has been conjured from.

Its funny us Corvette people are proud of the .92 or 1.00 G's but after driving the racing kart at 1.7G's just not the same anymore. But hey the vette still looks better.

 

Thank you Batman for proving my theory.

 

My guess here would be that 7" or 11" tires on such a small vehicle are probably running at extremely low pressures which would make for a large percentage of contact patch. Percentage wise, way more than we are able to get with our vettes. We can run lower pressure and get a larger contact patch but then the tires would fold under in hard cornering and defeat the purpose by reducing the contact. When I race my C5, I'm forced to run the tires with the maximum tire pressure just to help keep the contact patch flat on the ground from the outside to the inside.