Anybody know what's the widest tire you can put on an 8 1/2" Rim?
 

I picked up a set of v.1 18" 350z Track Edition Wheels. 8" +33 offset front, 8 1/2" 30 offset rear.

I know these come mounted with 225 front and 245 rear, and I have run 255's on 8" coupe wheels no probs.

I have a chance to pick up a set of good used Hoosier race tires, 285/30/18 and 225/40/18 really really cheap.

Question one becomes: Will the 285/30/18 fit on an 8 1/2" rim.
I [B]think[\B] the answer is, it's a bit too big but probably won't create a big problem.

Question two becomes: With this offset, will the 11" wide 285 tire rub the outer wheel well.
I [B]think[\B] the answer is: No it's going to rub.

Anybody know?

It won't rub, but there will be significant sidewall flex which can hurt performance more than help it do to sidewall rollover. Widest I would go with a set of road race tires is 275, on a street tire, I wouldn't go above 255

Most tire manufacturers will list the approved rim width for their tires, so it all depends. I'd guess that you will probably be limited to 265 and a big fat maybe 275.

Try messing around with this:
http://www.wheelsmaster.com/rt_specs.jsp

And see what it comes up with for tire widths.

You guys are confirming what I'm already thinking. 40 bucks for a set of half worn 285/30/18 and 225/40/18 Hoosiers though. I think they're R6, as they came off a formula type car. I'm going to go buy them. I can always sell or even throw away the 285's and use the 225's in front.

Anybody want to trade me 265's for my 285's???

225's are pretty narrow for the front, especially combined with the 285 rears, doesn't sound like a very good deal to me

My preference would be for 245 front and 265 rear but 225 ft 245 rears would certainly work ok and I don't think 225 ft 265 rear would create too bad an understeer bias although it might. I'm thinking that although the 225s are narrow I could use them and they're cheap.