Gears
 

What gears should I go with running 38's? I was thinking a 4.56 or 4.88. I want it to pull like it did before I put 38's on it and I still want be able to go 80 mph.

Joe would know best, He runs 37" tires and I'm not sure if he has swapped gearing in it. What gearing do you have now? 3.73? I would think 4.88 is gonna be a bit much but 4.56 should match pretty good to the tire size. What transmission do you have?

No more then 4.56's up to about 42" tires...

From stock to 37's I would stick with 3.73's or 4.10's, 37's and 38's 4.30's and then 38's up to 42's 4.56...

Its a Diesel, the TQ makes up for any loss due to the bigger tires. And you have limited RPM's to make any power.

i never got gears for mine (not yet atleast) but the ppl i talked to said if i ran 4.11s with my 37s it would be like stock tires on a 3.73.

Gears
 

Thanks guys I am gonna go with the 4.56 Just wanted to make sure. This is my first diesel to try to decide on gears for.

Re: Gears
 

I think I would go with 4.10s or 4.30s butthats just me. 4.56s just seem like they would be to low.

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Your mileage will be crap, just be prepared. When your crusing down the road you will be above 2000 RPM and that kills mileage.

not to steal his thread but i have a related question. as i said above the ppl ive talked to said 4.11s would put me back to stock gearing so my question is would running 4.11s spinning 37s kill my alrdy bad mileage

Yea I was thinking that it already sucks now. My dad has a97 powerstroke with a 5 speed and 4.10's with stock tires and I think it runs around 2500 at around 70 or 75 but it's pulling what ever you got behind it. That's the way I want mine to pull with 38's on it.

i think some 4.10s would do you well, if not 4.30s but thats as steep as i'd dare to go, you can always add more power too :tu: