I want to put new rims on my 1989 IROC Z and I will probably be getting either 17x8 or 18x8 IROC rims. I would like to have 18's but my question is will they fit and what size tire will I have to run? Also if any one has this setup and would like to post a pic that would be great.

 

I got 17x8 Centerlines with 245-45/17 all around the front is ok but I would not go any wider. The rear 255 or 275 depending on the clearance you have and the backspacing of the rims. I'm not sure about the IROC rims but you should be able to go 255 without any problems

 

I would go with the 17" Wheels/Tires unless you spending more money for the 18" Tires. I have 17x8.5 & 245/45/zr17 set up on my 87Z.

 

I have decided to go with the 17 inch rims with 245s in the front but I would really like to know how wide I can go in the rear keeping in mind it is a 8inch wide rim.