Who's done the 4:88 gear swap? What size tire you running?

 

A standard highway truck would have 3.55 gears with 265-70-17 tires which are 31.6 inch diameter. If your pulling or going off road somewhat, you might want 3.73 gears with those tires. If your off road most of the time, or pulling HEAVY load constant, then the 4.11 gears might be a good bet......... You 4.88 gears are .77 bigger than the 4.11 or close to 20% higher ratio... Compare that to the 31.6 inch tire, you could go 20% larger which would be 6 inches or a 38 inch diameter tire with the 4.88 gears........ your mileage will vary depending on what your goal is ????

 

I have 4:88s now running 35 nittos getting 12-13mpg by itself. Its a beast in the mud and towing my toys and camper. Just curious on who else has the same ratio and how well they perform with a different size tire. It's my daily driver and thought about going to 37s next but still undecided.

 

37s would probably be OK for medium towing and road use. When you get in the mud you will loose some of that bottom end GRUNT you have now. 35 to 37 is 2 inches or about 6% so that's not a lot of difference. At 2000 RPM, you will loose about 120 rpm with the bigger tires. The weight of the tires starts to have a greater effect when you start getting that big. I can only help from a design point of view. I don't have actual experience with that size tires. Maybe someone else will jump in.