Bob Cosby

The only thing keeping the 2010 GT500 from matching that 12.3 @ 117 mph timeslip is traction. The power to weight ratio easily supports that kind of performance.

Hmmm....why do I hook better with a 26x10 slick vice a 26x8 slick? Surely if they hooked the same, I'd take the 26x8, as it is lighter and has less contact patch, which reduces rolling resistance.

Wait - I just answered my own question!

Jay Peterson

Those car races are so macho...gotta love 'em - but down Main Street America? I'd look at the 0-60 time before anything else...the Camaro is a better car, it is awesome!

Bob Cosby

I don't race down mainstreet anything.

super83Z

This is exactly what I was thinking. The other guys make me go

99SilverSS

Really we could say this about a lot of cars. The SS's 110mph + traps mean the car could, traction permitting, get better ET's than 12.9's. But on that day and time for those drivers and cars on that track what we got was a good race regardless of price or rated power.

How many times have we seen coulda, woulda and shoulda get a big slice of humble pie at the strip.....



You are right on for the traction/contact patch/tire width. Maybe Haz will come back and explain what he meant.

JakeRobb

Bull****.

The physics you're using to explain your point are far too simple to catch the nuances that make you incorrect.

I'm no physicist, and I certainly don't pretend to understand this, but the fact is, however, that wider tires provide more traction, even at the same diameter. Hopefully somebody smarter than I am can come in and explain.

bossco

http://www.carbibles.com/tyre_bible_pg2.html

check out the section "Fat or thin? The question of contact patches and grip." To see what Haz is talking about.

A Bridgestone guy told me the same thing awhile back, changing to a wider tire changes the shape of the contact patch (increasing slip angle), but not its size.

super83Z

How much of that link is accurate if they can't spell tire?

I think this is another time when people are trying to be so smart that they outsmart themselves.

SSbaby

"Tyre" is the English spelling. "Tire" is the US spelling.

super83Z

Exactly we already know the rest of the world is dumber than us.

bossco

I'll have to see if I can stumble onto something by a major manufacturer, but it agrees with what the Bridgestone guy told me (even if he left the air pressure part out - the golden rule it seems is not to lower the pressure below the factory reccomendation if you want to avoid culpability as a seller/installer)

Here is some more debate on the subject (again with that crazy tyre spelling stuff )
http://www.eng-tips.com/viewthread.c...=102250&page=1

HAZ-Matt

I thought about not saying anything since nobody likes hearing it and because it seems almost counter-intuitive in a way. Obviously at the simplest level friction is not supposed to depend on surface area at all, but you are right in thinking that the simple model doesn't work for tires on concrete or asphalt. Essentially though the shape of the contact patch plays a huge role in how well you accelerate in any direction and widening the patch at the expense of length isn't going to help you in a straight line. bossco provided some very good links on the subject, even if they spell tire with a y.

Bob Cosby

I agree with the premise of this statement. In fact, it is easily seen in practice by comparing the real-world traction potential of a 26x10 slick versus a 28x10 slick. The 28" slick has much more hook, because it puts more tire on the asphalt.

My disagreement comes with the idea that a wider tire will result in a shorter contact patch that essentially negates the extra width. If that were the case, we drag racers would all be running soft compound temporary-spare sized tires.

Maybe I'm just too dumb to see it.

bossco

Yeah its tough to wrap one's mind around, but when you starting looking at it in terms of vehicle weight x air pressure = contact patch and divorce the physical dimensions of the tire from the equation it starts to make sense. Changing the dimensions of the tire effects the bias of the contact patch until you alter the air pressure, then the contact patch changes.

HAZ-Matt

Yeah. More or less exactly what I would have said. Makes you wonder why the stock recommended pressure in a 4th gen with identical tires all around is 30psi at all corners even though the weight is a bit higher in the front...

I don't want anyone to get the idea that I am a world class authority on the science of tires and I think there are too many variables for me to answer that one with any certainty. But the physical limits of the tire construction may prevent that. The longer the patch the more deformation there is and also the more rolling resistance. Perhaps these tires would end up slowing the cars by the end of the strip, or the extra sidewall deformation would lead to destroyed tires and higher than optimal temperatures.