Can I go higher on my rear end with 37's

[canuck rider]

I just bought a new to me dmax with a 3:73. I'm putting 37's on it and I really want to go with a higher ratio rear end for better MPH. I've heard that anything higher then what I have is really hard on trans and rear end axles etc with bigger tires. It's a pavement queen unless I'm sledding but I only pull 3 sometimes 4 sleds mostly 2 place trailer though. I'm not looking for 25+ MPH I know it's a truck not a prius just want 1-3 ish better.

Any one think it's ok. dumb idea, won't improve MPH, etc. What are your guys thought.

It's already got exhaust chip and intake. It's got plenty of power for what I do so if I lose a tiny bit that's ok to me . . . . For now

 

[freeflorider]

37s

Going to through this one out there, with 37s your changing the gear ratio all ready. Your rpm should fall with bigger tires and that alone will help you with your fuel mileage but with that in mind you'll need more power to turn them that means more fuel. Plus the added hight also adds more drag.
Unless your on a dead flat with a tail wind I'm thinking when your pulling a 4 place inclosed with a mod diesel your gonna get what you get....best to be easy on the throttle.
Happy pulling.

 

[Clumax]

Go to 410's

 

[canuck rider]

Thanks guys.

My dad had a Dodge with 4:10 Great farm truck, couldn't stand driving it on the freeway. I would always grab 5th gear right around 40 mile an hours. I kept looking for 6th, 7th and 8th

 

[zr600]

I would say 4.10s or even deeper yet with 37s. You said your dads had 4.10s and you were always looking for another gear when on the highway, what size of tires did he have that will make a big difference. If he had factory sized tires and 4.10s it would fell that way. With your big tires and factory gears it will actually change the gear ratio cause your tires are taller. So if you gear down bigger number the axles you will feel a power increase and maybe mileage increase cause the engine is running more efficeint. But remeber if its a 4x4 you have to do it to the front and rear too.

 

[turboless terry]

Bigger tire DO NOT help with fuel mileage. 37's will knock 2-3 off not gain you.

 

[dcooper]

The higher gear ratio given by the bigger tires will help but youll need some type of tuner to adjust for that because if you dont then your speedo and odo and mpg will all be wrong.

 

[turboless terry]

That is why everyone claims all the mpg. Looking at the feel good Guage. Larger tires don't help mileage period.

 

[XXL]

Here's my take, taller tires makes your spedo read slower and show that you are actually driving at a faster speed as what your speedo says (can you say speeding ticket?) and showing less miles traveled unless you can re-calibrate your speedo with a MiniMaxx or the trucks computer. It will screw up your milage figures so you think you are getting less milage. Really tall and really wide tires will mess you up for lots of reasons, roational weight, way taller and wider vehicle profile bucking the wind.

 

[Braaap12]

id go 4:56s for 37s

 

[Dogmeat]

id go 4:56s for 37s

This.

You want your final drive ratio to be as close to stock as possible.

Also, whoever told you it was harder on your transmission to put lower (numerically higher) gears in after running bigger tires didn't know what they were talking about, its exactly the opposite of that. You're loading your drive train up more having to turn the bigger tires without gearing down.

Simple math:

31.6 (stock tire height) / 3.73 = 8.471

37 (new height) / 8.471 = 4.36 ...

So really, a set of 4.30 gears might be your best bet, but it wouldn't hurt at all to go a little deeper with the 4.56's.