I have stock 1997 gt wheels on my car i think they are17x8s, correct me if im wrong. i was wondering if it could get a 315 on the back? i want to leave the 245s on the front but i want more tire in the rear.

 

315 on an 8" wide wheel is too much. I would recommend at a 10" wide wheel, especially since it's a lower profile tire.

 

what are the downfalls?

 

A 315 is going to be fine on your car, although pushing the limits of clearance, but will be an EXTEMELY POOR fit on an 8" wheel and to which Socal is referring). Is this what you were considering or getting a new set of wheels? Here is an example if a 315 on an 8" wheel:


The issue with above is extreme strain on the sidewalls and excessively poor handling on a corner. The tire bead has little contact with rim on wheel and prone to failure if you pitch the rear end out or spin the wheels.

New wheels are cheap and lots of styles in which to choose. See Choosing a new tire thread (sticky) and has the issues needed to be addressed by new wheels and some thoughts on what type tires to puchase and why. There are also some good links to site sponsors for purchasing all this cool stuff.

Jazzer

 

ive got 255s on the back of my 17x8s...dont really bulge at all so u might be able to fit a 265 on there..or like the rest of them said just invest in larger rims