There is some interesting information in: "When I switched to the BFG AT 37" tires my RPM dropped to 1900rpm and my fuel economy stayed exactly the same."
If this reference is when hauling the Lance camper or when driving unloaded, it would tell you different things and would point one toward the best tire diameter for loaded towing.
Did your mileage increase from the factory tires to the first oversize? Factory tires probably 32 or so?
I bet the exhaust gas temp was lower when pulling more rpm. More air and same fuel. Cooler. Longer life? More reciprocating wear? Shorter life?
If your truck has a instant fuel consumption meter it would interesting to drive a given section of roadway in overdrive while pulling the loaded trailer and then again in the next lower gear and compare the readout, even at several mph readings. Could tell alot on gearing and especially helpful if you know the actual transmission gear ratios. A little number work and you'd have the correct tire diameter for your desires.
If I would buy a 37 inch tire (roadwork) it would be narrow in profile. That will also help.
Marv
