Wheel and tire questions
 

A buddy of mine has a 2002 Ws6 firebird with 275 40r17 tires. Does anyone know what the backspacing on the wheels is? And how large can he go without having to roll the fender lip or tub it?

i am pretty sure you can go 11 inch rim and a tire size of 315 on a 17 inch rim with no mods, rear only.

A lot of the SCCA/NASA guys are running 17x11's with 315's at both ends of the car.

FRRAX has a great write up on the fitment and related consequences---> http://www.frrax.com/rrforum/index.php?showtopic=2922 Please remember when reading this that these guys are talking about racing applications. On a street car a lot of the wear referenced will take long to show up.

I have never driven a car with that much rubber. I can tell you just adding a set of real one season tires will make a night and day difference with the 275's. I would suggest before going to large by huge wheel and tires get adjustable everything and use it to perfectly center and square the suspension at ride height.

If you have more questions about the consequences of big wheels hit up Paul from CTW (Sponsor on side bar-->>>) he has a lot of knowledge and data to back up how more tire can change balance and grip levels.

-Tim

You can fit a 275 in front and a 315 in back with the right wheels pretty easily. Problem is that 315-35-17 tire selection is not good - only about 5 tires that comes in both 275 and 315 sizes to match.

I have seen a few cars with 315 all around - either in 17" or 18", but you will have to make some modifications and sacrifices to do that. The result is an ungodly amount of front end turn in and at the limit traction with the 315s on all 4 corners. Going from a 275 to a 315 all around is about the same increase in grip of going from a 245 to a 275, which is a big improvement.

One thing to realize is that front heavy cars like the f-bodies handle best with a square tire setup (same size in all 4 corners), which limits oversteer and increases mechanical grip. So either 275 (easy) or 315 in all 4 corners.

As Tim mentioned, there can be a huge increase in grip from going from a 275 all season tire to a top of the line summer tire, sometimes approaching 10%!