Im prepping to do some work on my diffs and I figured I ought to give some consideration to a re-gear while im in there.

I know 235/85 tires don't really need a re-gear for street driving (truck drives just fine right now), but I want to get some opinions from those that have gone this route. Do you feel the investment worth it? Is the engine noise at the higher RPMs bothersome? How much of a hit are you taking on mpg?

I wrote to Ashcroft and Dave's reply is that I would be best served going with 4.12, esp. with a D1 that has heavy bumpers and a rack.

 

I have 4.12s and 255/85/r16 and its definitely over geared for highway cruising rpms. i think i hover around 3k rpm on the highway and get 12mpg highway. I dont really mind it because i do have a bunch of weight from bumpers, sliders, skids, and roof rack but it feels a little over geared and makes me want to go with 35's next. Have you tried the ascrosft calculator? its pretty helpful tool.

 

Yea I’ve used it extensively.

What speeds do you cruise at on the highway? 3k RPM is around 80 for you, right?

I can’t imagine really doing much than 70, which makes me feel like 4.12 is acceptable.

 

Spoke with Bill at Great Basin Rovers for several hours today and ended up with a set of GBR 4.11 gears and TrueTracs front and rear.

With 235/85R16 tires, ill be at ~2,500 RPM at 65 and ~2700 at 70. This is totally fine by me as I already don't drive over 70 much. Frankly, I don't notice much engine noise until it gets up beyond 2,800 and even then, it's not annoying until 3,000. Had I gone 3.9, which GBR uniquely offers, I would have taken the truck back to stock, which would have been great for road driving, but probably frustrating on steep grades when fully loaded.