What is the maxium size tire I can put on my 96 Z28? Currently I have mounted Goodyear Eagle M&S tires. 275/40/18. A little rub now. I need to get rid of these winter tires!

 

Generally best to match the stock tire diameter. Your car left the factory with either 235/55-16 (26.2") or 245/50-16 (25.7"). Even the SS with the 275/40-17 tires used the 25.7" diameter.

The question is why would the 275/40-18 (26.7") rub? It only sticks up 1/4" further into the wheel weels than a stock 235/55-16. Has the car been lowered? What is the width and offset of the C5 wheels you are using? What are the tires rubbing on? On both sides equally, or mostly on one side of the car?

I run 28" slicks without rubbing on anything, at least after moving the rear axle assembly back about 1/4" to prevent the slight rubbing that occured when tire growth at 125MPH trap speeds became a problem.