When I had 3.55's in mine, I towed my camper (on 2 different trips) to both coasts. First trip was 4500 miles and went through the Rockies. Second trip was 7500 miles and came through from Fredericton, New Brunswick to Boston and on through Chicago on my way home. Worked fine for me. Last summer I was pulling the same trailer even with the 37's and 3.55's. I'm likely putting them back in once I have the gears for the front.