the physics of tire traction.....read if buying tires!

[FuryCharger]

Its amazing what college physics will do for you. In terms of traction, it is all dependent on the friction that the tire emitts. This is called the coeffient of friction. The formula for friction is (Normal force)x(coefficent of friction). The normal force is technically the force that the earth pushes back onto the car from the weight of the rear tires on the vehicle. In laymens terms, the normal force is how hard the rear tires are being pushed onto the ground. This is where LCA's, panhard rod, ect. come into play. They all give the rear alxe a firmer push onto the ground resulting in a greater normal force. In order to achieve a better coefficient of friction all you need is for a "rougher" tire design that "catches" the road better. looking at this formula, the tire width is obsolete, many people think that the wider the tire the more traction you have. That is a myth, all a wider tire gives you is bragging rights. You could have the skinniest tire ever produced with a strong rough coefficient of friction and you could have just as much traction as a corvette. When purchasing tires, dont be focused so much on the width of a tire but what ur overall plan is. if you plan on buying a ton of suspension products then you dont need the most expensive tire out there. If not then make sure the tires you buy have a high dry traction rating.

[BIG8]

Very interesting! This gives some insight as to why those Marangoni Zeta's (Italian version of GY F1's) are harder to break than the o'l Wal-Mart Goodyears, being of a softer compound ofcourse. Note: Zeta's are not quite as wide as the GY's.
Some good info though.

[V6Bob]

You have a good point, but you take it too far. That physics formula is not exactly true in the real world, but is a theoretical ideal which applies best to relatively smooth and hard surfaces.

With a rubber tire squeezed into irregular pavement some of the forces are not vertical (normal), but are parallel to the road. It's almost like gear teeth meshing. The more you have (ie the wider the tire), the better.

So width does count some, along with the coefficient of friction (and the tire construction and...). Given the same rubber and tire construction a wide tire will work better than a narrower one.

But you're correct in that discussions here are often too focused on width. People often say 255s are better than 245s. A good 245 will beat an average 255 every day.

[Tyler]

im happy with my 245's.. and for some reason im having trouble breaking loose in my moms camaro with 235's

[Turbo V6 Camaro]

my 275 grip like a mofo, but there abou 200 PER tire lol

[Dominic]

V6Bob is exactly correct [img]smile.gif[/img]

You're learning baby physics but its good stuff to know, and is relatively accurate. When it comes to cars though, wider is better and better for a few reasons V6Bob mentioned.

[ellik]

.....and with winter coming on us (at least those of us that drive our RWD's in the snow) the rules change yet again. the wide tires that we enjoy during the summer distribute the weight of the car over a larger area and apply less force to the slick ground, giving less traction than narrower rugged designed snow tires.

[oil pan 4]

The tire griping in the pavement, just think of when you drive on wet road and then go into a parking lot and go over a wet plate of steel. You get instant sliping becasue of the flat surface.

[TheStupidFock]

but for the winter tires, we dont really need to get thinner tires all around, or even just switch to winter tires all around, just one good winter tire and put it on the driving wheel (for my '96 camaro it the rear passenger)

[V6Bob]

OK if you don't have to turn or stop. :D

I know it's expensive, but, if you're driving a f-body in winter in snow country, 4 serious snows (Blizzaks or equivalent) are a good thing to have.

[KBeezy]

I have 10 1/2" wide tires on the rear of my car. Why? More of a contact patch with the ground [img]smile.gif[/img] So in the long run I'll be able to do A LOT more with those 10 1/2" tires than someone with a 9" or 8 1/2" tire...

[FuryCharger]

hey kevin....ur actually worng in that assumption. thats what I was trying to say, in the long run the amount of contact area the tire has doesnt make any bit of difference because that is not what determines how much friction and traction the car has.

[HAZ-Matt]

Originally posted by FuryCharger:
hey kevin....ur actually worng in that assumption. thats what I was trying to say, in the long run the amount of contact area the tire has doesnt make any bit of difference because that is not what determines how much friction and traction the car has.

No, no, no, no, no. Maybe if we lived in Physics 101 world where everything is a perfectly regular sphere. The problem with idealized friction is that it applies best to hard objects with little or no deformation.

http://www.insideracingtechnology.com/tirebkexerpt1.htm

That gives a fairly good explanation.

[KBeezy]

So you're telling me that two identicle Camaros, one with 245 wide rear tires and one with 275 rear tires have the same traction? LOL! Not in auto racing!

[V6Bob]

"the amount of contact area the tire has doesnt make any bit of difference"

"Camaros, one with 245 wide rear tires and one with 275 rear tires have the same traction? LOL! Not in auto racing!"

Guys, width is not nothing. And it's not everything, either.

Think the 275 will always win? OK, I'm putting you on 275-40-17 Sumitomo HTR+ and me on 245-40-17 Hoosier R3S04. Track day at Sears Point. Buh-bye. :D

People talk width here like it's everything, without mentioning the tires involved. Drives me nuts.