35's to 37's

[jfann10]

I'm fixin to buy some new tires and am going with a 37. I have 35's on it now Is it gonna knock my speedo off by much? And will i need to change my gears? Thanks

[terryknight]

you'll be off 5.7% over your 35s assuming you have already corrected for 35 from stock or 16.6% over stock

if you have 3.55s you would need to regear, if you have 4.10s you maybe able to get away without, but i would

[7.3550Duty]

Yeah i would reccommend regearing for sure on 37's. At least 4.11 if not 4.30s. I went with 4.56s wishing i went with 4.30s alil better on the highway but its all what your gonna do with your truck after you put the 37s on it. Like tow alot or just drive it everyday??

[700xxmaniac]

I have 395/75r16 mtz's with 3:73, the 7.3 got the torque to lug the truck up hills in O/D... but if ya run like my set up get ya Gota learn to get into lock up before any hills or else the tranny temps will climb faster then the space shuttle. And when that happens you'll get some practice at replacing the pump seal that blows when the boiling hot fluid returns form the unlocked converter...
4:30 gears and 35's are next on my list of upgrades...


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[STROKED_NY_023]

I am running 37's with 4.10 gears and it does fine. My last truck I had 37's with 3.73 gears, it did fine when a DD, but was a dog when towing.

As my truck sits now I am running about 8mph faster than what my Speedo reads, and turning 2k at 70. Hand calculated I am getting 19-21mpgs if I keep my foot out of it.

I also tow heavy (about 12k) without issues, have never been over 900° on the tranny temps.

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[jfann10]

Its mostly a daily driver. I very rarely tow but when i do its usually just 1-2 tons.

[jfann10]

And how much would switching to 4:10's cost? lol I'm kind of a noob at this stuff.

[erics diesel]

what gears do you have now? iirc if you have 3.55 to go to 4.10 you need new carriers to which adds more to the cost

[jfann10]

Well im not sure. i'm turning about 2150 rpms at at 70

[351fifty]

Originally Posted by STROKED_NY_023

I am running 37's with 4.10 gears and it does fine. My last truck I had 37's with 3.73 gears, it did fine when a DD, but was a dog when towing.

As my truck sits now I am running about 8mph faster than what my Speedo reads, and turning 2k at 70. Hand calculated I am getting 19-21mpgs if I keep my foot out of it.

I also tow heavy (about 12k) without issues, have never been over 900° on the tranny temps.

Sent from my SPH-D710 using AutoGuide.com App

900* trans temp? holy cow how did you get it past 250*? do you mean egt? lol

Originally Posted by jfann10

Well im not sure. i'm turning about 2150 rpms at at 70

sounds like 4.10's if you have 35's now and turning that kause with my 315's i turn a lil under 2500 rpm and i have 4.10's and LS
check your door code $5 says that it would read c4 as your axle code or c5 something like that