I have a set of magnum 500 styled rims size 15" x 7". What is the proper tire sizing for a 68 coupe?

 

I'm surprised DodgeStang hasn't chimed in with his chart. But, here it is, and all the credit is due to DS. http://www.dodgestang.com/Tire%20Fit...ide%2067-8.pdf

 

Thanks...that chart is great!

Correct me if I'm wrong. The maximum tire size I could go with my car is 225/60R15. But I could go smaller in tred width, maybe 215 or 205) right? Or is this size the size I shoud get? I'm not looking to race the car. It is basically a Sunday car with my kids?

 

You could get 245/60/15 on there if you wanted to but to answer your question, yes, you can go with a 215 or 205 tire.
What mustang are those rims from? The '68 mustangs only can with 14" rims unless it was the shelby which got the E70-15 tires.

 

Depends ALOT on the backspacing of the rims and what brakes you are running.

Assuming you have the stock drums, a 215 will work just fine for you with the assumption that the Magmun 500s have a 3.75 backspacing.

 

I have drum brakes all around and the backspacing of the mags is 4-1/4".

 

The you can go up to a 225 for sure without a problem.