I put rubi stk rock rails on my Sahara. With my 35's, I could not fit my smallish hand between the tire and the rail end. I read somewhere, that under compression, the tire rotates back a tad, and that the room is not an issue, BUT why bother....
It is super-easy to trim with a saws-all. I trimmed 2" off , slightly angled and then silicon-gasket'ed the plastic caps back on. ( blk silicon ) While I was down there, I went ahead and saw-alled the body crimp in the rear wheel-well too to follow the contour of the well/ tire. Then i sealed that cut with the silicon-gasket stuff. Came out great.
The clearance between the tire and body/rail is just too close unmodified if you ask me, especially considering the ease of modification and the downside of a damaged tire... @ 35", they are wayyyyyy too expensive to risk it.
'09 JK Unlimited Sahara ( sold )
'97 TJ (sold )