The steel belts in the SX tires are to help with the tread squirm (they did hug the corners very good) with the bias ply construction and also for puncture resistance (although I did have one on-road puncture with a piece of metal, never had a problem off-road). Mine (33x15.50 SX) were bad on the road, 2 were 3/8" out of round the other two about 1/4". Had them remounted, then shaved on the truck, all was fairly good until I swapped axles in back (and lost the registration marks), went back to a bit out of round. Also lost about 1 gear on the road, hills I could do in 4th gear with radials needed 3rd gear with the Swampers and I also lost about 20% gas mileage with the bias ply, again this was w/ 15.50 wide tires on 10" rims.