Sorry, i meant 5.13 gears. I think 5.38s would be over kill but i'll check em out. My buddy runs 4.88s with 41s and they are geared real well with em. But thanks for the advice. I'll look into it.
You will be perfect!
Let's do some quick math.
Using the following formula; [ gear ratio x speed in mph x 336 (constant)] divided tire diameter in inches = engine rpm in 1 to 1 gear (otherwise 3rd) Note: multiply by overdrive ratio to get actual engine rpm.
So stock your tires were 315/70R17 ( Here's another quick formula for you to go from a metric sizing to standard; treadwidth x profile in % x 2 divided 25.4 (to change it to inches) + rim diameter in inches. So (315 x 0.70 x 2)/25.4 + 17 = 34.36 inches as the actual diameter of your tire. Remove another 0.75inches to give you the approximate installed height and you get 33.61inches.
So back to the original equation;
For stock tires and gears;
(4.10 x 60mph x 336)/ 33.6 inches = 2460rpm in 3rd ....... 2460 x 0.69 (overdrive) = 1697rpm in overdrive.
For your new Beast 42.5 Boggers and stock gears; (I will say 42.5inches overall height since a bias ply doesn't squat like a radial!)
(4.10 x 60mph x 336/ 42.5inches = 1944rpm in 3rd .......... 1944 x 0.69 = 1341rpm = WAY TOO LOW!!!!
With your three options;
For your new Beast 42.5 Boggers and 4.88 gears;
(4.88x 60mph x 336/ 42.5inches = 2315rpm in 3rd .......... 2315 x 0.69 = 1597rpm = Still below stock rpm so better than the 4.10s with these tires but not good enough!
For your new Beast 42.5 Boggers and 5.13 gears;
(5.13x 60mph x 336/ 42.5inches = 2433rpm in 3rd .......... 2433 x 0.69 = 1679rpm = Still below stock rpm so better than the 4.10s with these tires and better than the 4.88s but still no performance benefit we are still working to simply gain back what was lost!
For your new Beast 42.5 Boggers and 5.38 gears;
(5.38x 60mph x 336/ 42.5inches = 2552rpm in 3rd .......... 2552 x 0.69 = 1760rpm = We have finally gotten over the stock performance hump and actually got your tires spinning and your engine and transmission happier!
I am assuming that based on your location and your truck set-up you run DEEP Mud...the 5.38s combined with a high stall torque around 2800rpm will make your H2 rule the swamps!
Mine rules the roost up here and I am only running 39inch XMLs! But I do have 5.38s and the high stall torque at 2800rpm. Trust me the big tractor tire rigs will be having you pull them out!
I know this was lots of math BUT I hope it will help you make a more informed decision.
Kev
On a side note....any vids of your Monster Running some Mud????? PLEASE!!!! I would love to see your Beast tearing it up!