retiree

Based on a given tire circonference, air pressure, car weight etc, would road contact surface area increase with a wider tire while retaining the same tire circonference?

I have asked many people and some say that a wider tire does not increase road contact surface area!?!?!?

Anyone can shine a light on this one ?

Thanks

NSXDreamer

I have asked many people and some say that a wider tire does not increase road contact surface area!?!?!?

whoever said that really is bs sing u...

you need to understand what is the contact patch... contact patch is the area the rubber from your tire actual touching the ground, so the wider the tire will give you more area, thus more contact patch...

However there's some other things that will affect the contact patch and that's probably why people got confused...

Different tire model and design does make a difference on the contact patch, generally today's racing tire that had a more square sidewall provide more contact area to the ground. So if you look at your mom's Suv's tires (say it's a 225/70/15 touring SUV tires.) probably have less contact area than your brother's Civic's "performance tires that only had a 205/40/17 size...

tire circumference doesn't affect the contact patch but matters lots of problems, ie. rubbing, centrifical weight/force, ABS/ TCS modulations....etc.

Air pressure and Car weight, it's marginally affect the contact surface but your manufacuturer suggestion on the air pressure already factor in the car weight, and I would ask when you upgrade to different tires you probably want to start off with the factory spec first right? (it's a good idea to never run less psi than the factory suggestion though...)

lastly, just a little common sense, if wider tires don't give you more grip ( result of more contact area ) then why people want to put widers tires on High powered cars?? Or else, Why not manufacturer start putting 9 inches wide tires on their econo car??

In all production cars we have the same problem of only fitting a given max. width of the tires under the fender well without extensive modifications... and we have heard people start choosing some "rounder" tires to try to get away rubbing, in that case a wider tires had been chosen for its apprerace only because at that point more contact patch means more problems for them... in the other words, we do have a limit of the given width of the tires due to the car design...

now you probably understand why "wide body" is hot for some high performance cars because they need more rubber!!!

retiree

Thanks NSX for this explanation. Now, what if I had say 205 wide tires and went to 225 with the right profile to retain the same tire circonference. Would the contact patch area still increase?

retiree

Got a good answer from the other site ! Check out this link:

http://boson.physics.sc.edu/~rjones/...efriction.html

Now I can argue with that engineer !!!!

Comet2404

I'm just confused... as long as my tires stay on the road, and where I point them, I'm happy!

NSXDreamer

retiree, I'm no engineer nor any tire expert, I just know a little more about these stuffs than normal people...

the tire circomference really have nothing to do with your contact patch...

back to your old question, with the same tire design, the wider the tires are, the bigger the tire's contact patch are...

I hope this straight forward answer won't confused you as "the lecture" i posted last night did.

retiree

Starting to make sense. I still sent an email to Michelin to get their point of view. Will provide their answer when I get it..

Thanks