Tire question;

[Maddog]

One a heavy pig like my Z28, given the tire choices I have, is it better to go a little narrower on the thread width with a shorter profile or wider thread width with higher sidewall profile i.e. 245/45/16 or 255/50/16? I guess my question is...contact patch more important than sidewall flex or vice versa?

[Burnsey]

Hrmmmm...for AutoX...I would vote for width...I wonder if a few extra PSI would help compensate for the less-rigid sidewall.

But then again, I wouldn't take tire advice from someone who drives a FWD four-door sedan :p

[Marsh]

Remember bigger tire does NOT mean bigger contact patch. Contact patch size is a function of weight and tire pressure (with a small dependence on side wall stiffness).

Wider tires only effect the SHAPE of the contact patch. But wider tires make for better contact patch shape to be sure. Also shorter sidewall does not necessarily mean stiffer side wall.

But your also leaving out diameter. The 245/45/16 will be reasonably shorter than the other thus giving gearing advantage. For this reason I would go with the 245. Shorter, theoretically stiffer and not really much different in width than the 255.

[Doug Phillips]

I know you are not talking about snow tires! Take some of thay pretty paint off and save some weight.

You are running a lot of power. I would go wider, depending on your rims.

Whattires are you looking at?

No 17 inch bling?

[Maddog]

Well, I have 18"s for my street tires now, so I'll be using the stock Z28 16" wheels for the race rubber. They're 16x8 so I can't really go wider than 255, or maybe 265 (Hoosiers).

[Guillermo]

I noticed nobody has mentioned load rating yet.
The 245/45/16 is a smaller diameter tire that will have a much lower load rating compared to a 255/50/16 of the same tire model. Those with Miatas and old Hondas don't need to worry about load rating, but people with heavy cars like Camaros, Talons and Subarus need to make sure the load rating is adequate or else the tire sidewall will not be stiff enough to support the car under hard cornering forces. Someone with tires with an inadequate load rating for their car will be forced to use much higher air pressures to help reduce sidewall flex but the extremely high pressures will reduce the contact patch size and therefore reduce the grip.
For a heavy car like yours the 255/50/16 tires may work better then 245/45/16 for autoslaloms or track events due to the higher load rating and the wider contact patch. But if the 245/45/16 tire has a more then adequate load rating for your car then it may work better because it should fit on a 8" wide rim better providing stiffer sidewalls and better gearing as Marshall suggested above. The best way to determine which one is better is to buy both and test them out ;)

[Pete@Marcor]

I noticed nobody has mentioned load rating yet.
The 245/45/16 is a smaller diameter tire that will have a much lower load rating compared to a 255/50/16 of the same tire model. Those with Miatas and old Hondas don't need to worry about load rating, but people with heavy cars like Camaros, Talons and Subarus need to make sure the load rating is adequate or else the tire sidewall will not be stiff enough to support the car under hard cornering forces. Someone with tires with an inadequate load rating for their car will be forced to use much higher air pressures to help reduce sidewall flex but the extremely high pressures will reduce the contact patch size and therefore reduce the grip.
For a heavy car like yours the 255/50/16 tires may work better then 245/45/16 for autoslaloms or track events due to the higher load rating and the wider contact patch. But if the 245/45/16 tire has a more then adequate load rating for your car then it may work better because it should fit on a 8" wide rim better providing stiffer sidewalls and better gearing as Marshall suggested above. The best way to determine which one is better is to buy both and test them out ;)

It is generally hard to overheat or overload a tire in an autocross. The gearing advantage would be pretty big, as the 245/45 is about 9.5% smaller in OD than the 255/50R16. This would be the same as a step in a rear axle ratio, approximately.

In fact, it was not uncommon to see Stock class 5.0L Mustangs on 225/50R15s back when they were popular.


If you were using this on track, I would suggest 255/50R16s without question.

[13inches]

Why not run the 315/40/19 Hoosier A6 instead? Its only $165/corner.

https://www.hoosiertire.com/ecommerce/Products.asp?SubCatID=17

I'm sure you can tub the car..... :)

[Maddog]

I'm not to worried about the lower gearing aspect since I already have 3.73 gears, and 300+ RWTQ from 2500-5500 RPM ..lol But the reason I was also thinking of the shorter tires is to also drop the CG.

Thanks for the input fellas.

Decisions, decisions.