Rim Choice with Dr. Diff's 13" Brakes
Ok, with 275’s, 18x9’s with a +35 offset and rear disks will be pretty close to the springs with the stock spring location. You
might need a small spacer.
I run a 68-70 B 8 3/4 with the 11.7” rear disks and 18x10’s with a +38 offset and 295/40/18’s. But I also run a 1/2” spring offset. The math says the 275’s and 9” rims should clear without the 1/2” offset, but, it will be close enough that I’d say you’ll have to mount it up and see for sure. Especially considering it’s an aftermarket S60 rear being compared to a factory 8 3/4. Fortunately, if it’s a little too tight a small spacer should solve the issue.
