Street Tires

[LarryJM]

Read several items on g force and street tires. That is most street tires can not do much better then .55Gs of acceleration or about 0-60 in about 4.5 seconds. That is what I get in second gear on run flat tires. They more or less stick to the road and I get about .55Gs of acceleration. First gear is another story. I can get it up to .6Gs but with lots of wheel spin. It's said that I can get it over .7gs with M/T drag slicks rated about 100 tread wear vis typical 400 tread wear rating.

So it seems the tread wear rating is what makes the tire stick to the road and not width. A 235 tire with a tread wear of 100 is way better for acceleration then a 275 tire with a tread wear of 350.

 

[Norm Peterson]

Compound almost always beats width.***

But until you get into seriously sticky tires (drag radials and up) on a prepared launch pad, any front engine/RWD car is going to be limited in how much forward acceleration is possible.

Let's assume your tires on some pavement will be good for 1.0g, that your car weighs 3700 lbs with you in it, at 54/46 front to rear weight distribution.

Your car's weight distribution puts only 46% of that weight over the rear tires. So now you have 0.46 x 3700 lbs of traction available to push 3700 lbs . . . only 0.46g


Yup, you've got some rearward load transfer helping that out, so let's assume a 21" CG height and a 107" wheelbase. The math gets a bit more complicated, something like

a/g = 0.46 / (1 - 21/107), or about 0.57g



*** tire width alone affects grip by about the 0.15 power, maybe 0.2 power. 25% wider might buy you 5% more grip, holding everything else constant. There are other factors at play, however.


Norm