I had some BFG's (31 's) and I know that the dimensions printed on the side is just for decoration. So what's the 35's real size? How bout the 36x12.5 SS SX's? Thanks

According to the sites for both:

BFG - actual is 34.1"

SX - actual is 36.2"

I believe both are mounted on 15 x 10's.

You can mount the BFG 35x12.50's on 15x8 or 15x10, The Swampers need the 10 inch wide rim I believe