Owner of a cummins 5.9L powered 2006 Dodge Ram 2500 4X4, currently running 3:73's. I'm getting ready to install 37" toyo mt's and want to upgrade the gears, the truck is used 70% daily driver and 30% mix off road and towing.

Anyone have experience with this? Thinking either 4:10 or 4:56; feel like I'm undergearing a little with the 4:10 and overgearing a little with the 4:56...thoughts on how to proceed would be much appreciated.

Thanks,

Lucky

 

410 will be plenty steep especially for a dd. I have 35's with 373 and it still drives and tows great. I like that it runs a few less r's goin down the road anyways

 

If you go to a gear calculator and pull in the stock tire size and gear ratio and the new tire size it will tell you what size gears to go to keep as close with the stock ratio. my first lift on my 02 ford f250 with the 7.3L psd was a rubicon 6.5" lift and I went with 37" tires and changed my gears to 4:30. If you don`r regears at all you will notice a huge differance from stock tire size and gear ratio. You mpg and tranny will thank you. Gear Calculator: Use Our Gear Calculator for Proper Gear Ratios

 

I think you would be okay with 3.73's... 4.10's would prob be a little better though

 

New tire divided by stock tire = rate of change.

Rate of change times OEM gear = new gear.

37/31.5=1.175
1.175 x 3.73=4.38275

4.11 or 4.56 would be your choices making your assumptions about gearing 100% correct. Given your driving needs, I would go 4.11.

 

There ya go. Gotta love math