225/45/15 vs 255/40/17
 

I am in STX.
I am facing a tough fight in my club's autox. Please help.

driving my wife's automatic FRS. I have Tein H-tech & Koni, rear control arm, front camber bolt. intake & cat-less front pipe. I don't want to spend more money on suspension or engine parts.

All else remains the same, how would you feel about:
255/40/17 vs 225/45/15 ???

BFG Rivals.
23" vs 25" diameter for better acceleration to compensate for longer gear ratio in automatic.
but 8.5" vs 9.5" treadwidth kinda counter-intuitive.

top speed in 2nd with the 225/45-15?

I have thought about doing this also, I just didn't want to invest in custom 15x9 wheels to find out.


Simmons

Front sway bar?

255/40/17 is too big. You'll lose acceleration

225/45/15 is too small. Like 10% less circumference. You may top out 2nd gear at 50 mph or so. It may work on a slow course. Even if it does, you may have brake fitment issues.

with 255/40/17 ... accelerate earlier without spinning the rear.
at 225/45/15... accelerate faster, but probably later to avoid spinning the rear.

i have a 22mm whiteline front sway bar, softest setting.

I run a auto in stx as well. I have been through 4 sets of race tires since last year. I ran two sets of 225/45/17 last year. Not enough tire.

This year I ran at the start of the year toyo r1rs in a 245/35/17 these were amazing and I may get them next year. They helped acceleration a ton. You still hit 60 in 2nd and its only 23 pounds. My 245/40/17 rs3s are also great. But weigh more.

Did the OP mean 225/45/17?

Nope. 225/45/15 is correct. 15". We know 15" wheels will fit. Just a matter of tire size dilemma.