just curious what rpm's people are running w/ 4.56 and 4.10 gears at highway speeds (70-75), and with what size tires. i've got 3.92 with 265/70/17 and turn just over 2000rpm at 70mph. i'm sure there is some triginometry equation i could use...but i'm not in school anymore and i drink too much. whenever i need new tires i'm going to be getting 33's and am just wanderingwhat rmp's i'll be turning on the highway.

thanks

 

The 265/70/17 tires are 31.7" tall. There should be some kind of calculator available on the web to calculate the diffference.

 

Here's a link to one
rpm versus gear versus tire diameter
Java calculator:

http://pw1.netcom.com/~sgalaba/mph.htm#GearSpeed

When you calculate a tire diameter
reduce the size you get from the official sidewall numbers
by about 5%
this is to correct for the 'flat spot' at the bottom of the tire
where it touches the pavement
and will make the speeds and rpms more accurate.