i have billstein 5500 series shocks on all corners already and installing a set of air bags as well . im thinking of going with a E rated tire using 265/70/17 . the farthest i take the trailer is about 4.5 hours from home once a year other then that its 1.5 hour trips a couple times a year .

 

If I went from a 275/60/20 to 275/55/20, and I have the 3.92's, does it mean that with the 55's I now have roughly 4.10's? If the 55 is roughly 4% shorter, does that simply multiply by the gear ratio to get the effective ratio, or is there a different formula for figuring this out?

 

3.125% shorter and 4:04 gives an indirect rough estimate because tire diameter from one Manuf. to another will vary. Also, it doesn't effect the gearing as much as if you were to really have 4:04 gears. You would see significant changes in your torque curve compared to tire size change.

 

Thanks dirtydog.