Max tire size '71 Demon

[shobes]

For what it's worth, the 275 60 R15 on an 8.5" wide rim with 4-7/8" backspacing fit under my '75 Duster just fine. I have SS springs but in original location, still have a good 1/2" of clearance and since I race in straight lines should be good.

 

[screemin demon]

I just wanted to thank everyone for all the helpful input. Here's the finished product. 275 / 60 / 15 out back and 225 / 60 / 15 up front.