Is your truck stock? I had 35's on mine and it would tow 15000lbs over White Pass over the speed limit. I really liked the 3.50 and 235/85/16 for power towing, but the 35's worked really good on my old 12 valve.:redneck:
My current truck had 4:10's and 215's. If the truck was stock it pulled better but turned up the pump and the 3.50's felt needed so I could tow at freeway speeds, so they got switched to 3.50's.:redneck:
My truck is nothing wild by any means...
but....my point was simply about gearing and the speed limit.....my truck tows awsome at about 85mph in 6th......but doing 55 fawking mph through the Republic of Kalifornia puts me somewhere around 1400rpm's in 6th.....
I really like where I'm at......as I can lope along at 60-65mph around 1700, dump to 5th and pull most any hill at teh same speed at around 2400.....
but put much of a bigger tire on it, and its not going to ever be happy towing in 6th