Well, I recently moved from 35s to 37s. On my first trip with the 37s, I encounted a couple of issues that needed to be addressed: weak relay rod and lots of tire rubbing. I replaced my relay & tie rods with heavy duty Budbuilt rods, and reduced the size of my wheel sacers from 1.5" to 1" and installed a 1" body lift from 4Crawler to help with the rubbing. I went to a local moto track to flex and test the rubbing and so far it looks good. I won't know for sure until I hit the trails. Here is a before and after shot of the body lift installed.