I'm wanting to run about a 11"+ wide tire in my 78 Camaro. Probably a 285 x 40R x 18 which is 11.2" wide. Prefer not to roll the lip or modify if possible. But I've read that the largest tire to run in a stock Camaro is 275 x 40R x 17 which is 10.8" wide. I did some measuring on my car and it looks like I could get the 11.2" with proper back spacing etc. I'm measuring from my current tires which are 235 x 60R x 15 and are 9" wide. In photos you can see I have 1" clearance to rear fender lip and 1 5/8" clearance to the leaf spring. That adds up to 11 5/8" total so 11.2" should be just fine. Am I missing something?