rjrjrusa

Anybody have any comments on how a 2500 with 6.7 Cummins performs with 37x12.5 tires and 3.73 gears vs 35x12 Tires. Looking for information on typical power performance and Miles per Gallon. I do not tow much. The truck is being lifted 6 inches so clearance will be no problem.

djcheez

12.5 and 12 wide wont have any effect on your gearing. the 3.73's would be fine if you arent towing anything. it will be kinda a dog out of the hole but not too bad. with that setup it will be like havin 3.20's or so rear end ratio. mpg wont be great, and shouldnt be much difference between the 2 widths of tires.4.10's would be optimal for that tire IMO

Squidward

I'd go with 4:10's. Right now I'm running 35's with 3:73's, and if I had it to do all over again I'd have gotten the 4:10's.

rjrjrusa

I appreciate the comment. Unfortunatly I ordered the truck with 3.73 based on a few peoples recommendations that with the 6.7 Cummins it would be fine. When I tried to change them to 4.10 (contemplating getting 37" tires) it was too late. Do not really want to spend another couple grand to change them out so I guess I will stick with the 35's. Thanks. By the way, how is your gas mileage.

Squidward

Lots more tire choices with 35's anyway, good call. No real need to go up 6" to fit them though. I'm getting around 18 mpg unloaded and 11-15 towing, depending on load and speed, but keep in mind that I've got a 5.9 with 100k miles on it, so it's pretty well broken in by now. Based on what i've read about the 6.7 (especially a nice tight new one) it may be tough to duplicate those results. I'm talking real world hand calculated, not overhead guesstimated MPG.

djcheez

with EGR unplugged, i get 16 or so empty and 9.5 or so pulling a 15k 40ft trailer

BPoulsen

I have 35x12.50 with a 3.73 on mine, granted it's an 06, so I have the 48RE. If I could do it again, I would have got the 4.10's. With your 6-speed auto, I would think you are fine, just drop down a gear or 2 when you're towing.

roger.t

well with the 35 12.5 toyos that i have on i lost about 2 mpg. and a little acceleration but not much. making about 14 mpg calculated on the highway. city is closer to 12. but can very depending on how i drive.have seen myself get as low as 9 mph. oh and i have 3.73 gears.