A friend of mine has an 89 mazda rx-7 and he wants to switch his back tires with my front tires for the track on sat. I'm not sure but he says the lugs are the same so they will fit, just wondering if this would change anything on my car? will the weight difference matter or the less rubber on the ground? or would it not matter at all since its front tires, thanks
Bill

 

anyone??

 

The smaller your tires are up front the faster you will run in the 1/4 mile. Less rolling resistance, less friction, less air resistance, lighter tire.

 

Is it ok on our f-bodies to have 235's up front, and 255's in the back?

How much difference in ET would it make with smaller tires up front? Having larger tires in the back is good for traction correct?

 

There's a lot more than tire size that determines grip and things of that nature. Also the sidewall of the tire has a lot to do with lauching, or lateral grip. The higher sidewall provides better traction off the line because the tire will warp itself slightly, the lower sidewall provides better handling because of the lower amounts of tire flex. You can run 235's up front and 255's out back it'll make the car understeer if you do any sort of autocrossing though. When I said smaller tires, I mean like much smaller, like 205's or even some skinnies. A friend of mine went out and got a pair of 14 or 15 inch 5 lug wheels and put on some 185's (or 195's I can't remember) the wheels were a lot lighter as were the tires he picked up about .15 from it.

 

My ET improved by going to taller tires up front because they provide a longer rollout between the pre-stage and stage beams. Because of the rollout change the point that I react to the tree also changed (for the better in my case) which helped me with my overall R/T.

On the fronts, skinnier and lightweight is better. Diameter matters. On a regular car the sidewall height in the front doesn't matter, but it does make a big difference in the rear where taller sidewalls are better.

Increased air pressure in the fronts provides for less rolling resistance (friction) which is good.

 

Good point on the air pressure I forgot to mention that.