Im sure this has been asked before, but I couldnt find it in a search. I have a 2007 megacab with a 6" lift and 37" tires. I want to regear and need some help on what would be the best for me. I am a daily driver that does very little towing. any help would be great.

 

If you have the 3.73 like I do, I don't think you'll want to change your gearing. That's just about the optimal setup for those size tires and weight of the truck.

Anything higher and you'll max out on your rpm's and have no top end, and lower you'll be begging for rpm's.

I averaged 17 to 19mpg on a resent road trip. I'm sure you must be close to the same. You won't see those numbers if you change the gearing. I wasn't looking for mpg's when lifting the truck with huge tires but, because of some electronics and current gearing, it can be achieved.

 

I hate to say this but you are wrong. These trucks come from the factory set-up with the correct gear ratios for the size tires that come on them. A 37" tire changes the final drive ratio quite a bit. While you are correct in top end (as long as the engine can pull it), It is your low end that suffers. Which cause the auto tranny to work harder on take-off and having to slip the clutch more in a stick shift. You may also see the tranny "hunting" for gears on up hills to keep the engine in the proper "power zone".

A good example of this is my Toyota rock crawler. It came with 4:10 R & P’s; it came with 29” tires, when I moved up to 33” tires fifth gear became useless on the freeway. I changed the R & P’s to 4:88, which put it back to about the factory final drive ratio. I am now running a true 36 x 13.50 tire (IROKS) and on the freeway, fifth gear is useless (the engine does not have the power to pull it). This does not bother me because I trailer it. Once I am in the rocks it plays no part, I have dual T-cases stock gears in the front half aftermarket gears in the rear case, which puts my ratio at the output shafts at 200-1 if I need to go that low.

As far as aftermarket, I do not know of any one that makes them at this time. You may want to check Randy’s Ring and Pinion, if any one will have them it would be there.

 

When I lifted mine I went from 3.73 to 4.56. It does great until 98mph and it runs out of rpm's. Kinda embarassing to have all that power and some rice burner pass me up doing 110mph. If I had it do over I would have went with 4.10's