I'm thinking about buying some 275/45/17 what size rime ya think I need and off set I'm going to stay in the 17'' size. I'm not going to lower the car I'm going to keep the stock hight it on an evo 8

 

Try this...I use it all the time.

http://www.1010tires.com/tiresizecalculator.asp

 

how are you planning on getting those to fit under your fenders?

You want 9.5 at the minimum... 10 or 10.5 for better, non-bulgy look.

 

275 45 17 is a very tall tire too. you'll need something more like a 275 30 or 275 35 17. you'll need to roll the fenders, and as goofy said, you'll need wide rims. 17x10". i have 17x9" with 275 on my race car and the rim isn't wide enough for my taste. i plan on moving to a 10.5" wide rim.

 

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

You'll want a 35 or 40 aspect ratio if you plan to run 275 wide 17" tires.

 

For street use, road race, AX?

Unless you like slower acceleration and turn-in (weight of tire and width of contact), I would not got with that.

AX/HPDE - different story.

 

You've got wide fenders up front on the race car too Kevin.

I don't think that this width tire will fit correctly under the fenders (front or rear) with just a roll on the 8/9. It will 99% of the time look mexiflush rather than nice.

I know some people have made it work, but they've typically replaced their fenders and done very aggressive pulling as well.

 

yup, seibon widebody front fenders. ironically the problem i had was the offset of the rims i'm using put the tire into the shock. i had to run spacers, the fenders still don't look very filled

 

Those would look great on 13s.