89dieselkong

Here is my dilemma. Currently I am running 285/70R17 size tires on my truck. They fill the wheel wells ok, but the next size up would be better. I also tow a 40' 5th wheel when we go camping. My biggest concern is RPM when towing. At 65mph I am turning 1700RPM, which I think is a little low for best EGT/Economy. I find that if I go above 70 my EGT's drop and I am closer to 2000RPM. It also pull hills significantly better at that RPM. Usually I run up to about 60mph with OD off to keep my RPM in the sweet spot on slower roads. Otherwise it just lugs too much. Obviously going to stock size would be the best option, but looks wise I think it looks too small on a Mega Cab. How would running say a 295/70R17 or 285/74R17 work out. Basically I figure I went up an inch on tire size from stock and dropped 250RPM at the same speed. If I go up to either of those sizes I figure I get another inch and drop another 250RPM allowing me to run up to 65MPH in 3rd. Am I asking for too much? I really don't like towing over 65mph but I am right at the spot now where between 60 and 65MPH is either too high for 3rd gear or too low for OD. Thoughts???

kokalit

I have Hankook Dynapro RF10 295/70-17s. I lost about 1-2 mpg in my everyday driving. Had not had a chance to drive long distance or tow with them. Long distance highway not towing I think I would get great mpgs out of them. I see 70mph at about 1750 rpm now. With stock tires 70 was at 2000rpm.