What is the widest tire I can go with on a 17x8 rota boost wheel? 225? or 235 maybe?

245/40 (a little too short) or 245/45 (a little too tall). If you don't mind going outside tire manufacturer specs a bit, 255/40 is the same rolling diameter as stock.

I would run a 245/40 or 255/40 if I were you (assuming you have a sedan and have no clearance problems).

More information is needed about your car, suspension, goals, tires, etc.

I have a sedan with s-tech springs and kyb shocks. I'm just trying to get a nice stance instead of pushing these penny width tires.

Roll your rear fenders and 245/40.

I have a sedan with s-tech springs and kyb shocks. I'm just trying to get a nice stance instead of pushing these penny width tires.
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Set your Chapter to MAIC :)

2. If you want to make the car 2% faster, 235-40/17 gives you a nice gearing advantage and still looks fine on an 8" wheel.

john

....the following is a popular link to a tire size calculator that may help:

http://www.miata.net/garage/tirecalc.html

Compared to the stock 205/55/16 size, both the 245/40 and 255/40 are pretty close in diameter. If you go with a 225, you'll probably want a 45 profile. .....235 is a toss up since the variance between the 40 & 45 is nearly equal (one is smaller while the other is taller). ....John mentions the advantage of going with the 235/40.

I prefered the 235/40 with the 2.0.....

235/40 is plenty. im running it right now with fk451s. 255 is overkill for a DD

i'm running 235/40 on my 17x8 boosts. works great and no rubbing with tanabe springs. if you do 245 with those crappy s-techs you will probably rub.

josh

255 40 17 is what I would go with for all out grip...but those springs are going to hold you back no matter what you do, so you might as well do something easy like a 235 40 17.