Help with wheel choice 15" or 17"

Your going with a "custom" wheel, so get a custom look. The best of both world's is to put 15's on the front and 17's on the back.

It's not going to look extreme with 17's front and rear. Joe's '71 is a perfect example. That looks sharp!

Think of it this way, do you want to see 'tire' at the rear wheel opening? If so, put the 15's on. Any wheel size over a 15" is most likely going to fill the opening, hiding the top of the tire in the fenderwell.