I am wondering about what rpm i should be at at 65 mph with 285's. I aqm running at just over 2k. Is this right or is my tranny poopie.
Wording is always tricky, as it does not matter what size tire is on the truck the tac and the speedo will always read the same ie 2000rpm @ 65mph (as an example) the speedo will NOT read higher or lower just by changing tires.the speedo will read a little low with the over size tires...(about3-4%)
i run 285's with an auto and 3:54
i can run 70-72mph at 2000rpm
If you only lift one tire the drive shaft will spin twice as fast... and if you lift both tires one will go the opposite direction and the ds wont spin at all... so lift one tire, 8.2:1 is 4.10's and 7.1:1 is 3.55's...I think the OP should check his gears cause I have the exact same set up 285/75/16s and 4.10 and at 65mph I run about 2050 RPMs with a corrected speedometer. easiest way to check your gears (if you dont know, you may know) jack up the rear of the truck put a mark of some sort on the driveshaft, and spin your tires and count the revolutions of the drive shaft if you turn a little over 4 times then you obviously have 4.10s not 3.55s.