15x7.5 or 15x8, on M1, what is best performance choice

[alpinaturbo]

Brian

I have a FM II M1 1993 Miata, set up for dual duty- daily driver and track day.
Due to limited space under the fenders, I wanted to ask for your recommmendation in wheel and tire size for best track performance.

First, I think that the most tire I can fit under the front is 225/45/15.
The rear may be able to take 245/45x15? Can you advise, please, and what offset would be appropriate.

Next question is if a turbo Miata with 250rwhp can take advantage of the staggered tire width? 225/45 front and 245/45 rear? Is there a worth awhile advantage?

Would you recommend to run 15x7.5 all around, or do you see an advantage in running 15x8 in the rear to support the 245/45 tires better?

The other choice is to run 15x7.5 and 225/45x15 all around, and I am wondering how much more performance is there in running staggered more tire in the rear? Is it worth the "hassle" of increased cost and inability to rotate tires?

Thanks for your advice
Ivica

[Brian]

Sorry, nobody makes a 245/45/15 that I know of...

So, that would leave you with 225/45/15s for track day, which I would run at all four corners. Those certainly work well on 15x7.5...they work slightly better on 15x8 so the sidewalls are better supported for just a little sharper initial turn-in response.

The SSRs in 15x7.5 would make it easy to get the 225s under the fenders given the 43mm offset. The ATS complite would be a little more work (fender lip rolling), for a little better result.