My K1500 (5.7/4l60e) is getting lifted and geared in the near future. I plan to run 37x12.50r17 tires on NNBS stock alloys. I'm stuck trying to decide between 4.56 and 4.88.
I do probably 70/30 highway/city, only tow about once a month, and usually the towing is local. (building materials, trash to the dump, etc)
According to the Grim Jeeper calculator, and based on the claimed size of the tires I want (Toyo RT, 36.8"), my RPMs will be:
4.56 @ 70 = 2040 RPM
4.88 @ 70 = 2183 RPM
Currently I have 3.42s and 33s on steelies which sucks, since it keeps kicking in and out of 4th when the road has any incline. 4.56 would be very close to what it would have been stock with 245/75/16 and 3.73s, (2015 @ 70) which is how most of these trucks came stock.
Is ~2200 RPMs to high for sustained highway driving? Would the 4.56 get bogged down by the weight even though they "match" the stock setup numerically?
Is there a certain point in the rev range where the mileage starts to really tank?