4.56 or 4.88

Looking for suggestions...

I have 2006 DCLB 4x4 V6. I've added ATH Fab front/rear plate bumpers, and Leer camper shell. I'm adding ShmellFab sliders next week and doing the CMC. I plan to ad a winch (Warn 8000s) and full BAMF skids within the next 3 months. I'm currently lifted 2" and running 265/75/16. In about two weeks I will be switching to 295/75/16 BFG KO2 (33.40" tire), which are heavy tires, so I am going to do a gear swap.

I've spoken to a couple of reputable gear manufacturers/mechanics (MobileGear and Nitro) who both told that 4.56 would be a good gear choice for 295/75/16. It seems like a lot of guys in this forum are swapping out to 4.88 gears with 33" tires. Am I missing something, should I go with 4.56, or 4.88?

Please give me some detail why one or the other. Thanks!

 

I'd think little difference. If you have an auto. W/OD, the 4.56 with 33.40" tires will run 1927 rpm. @ 60 mph. The 4.88 with 33.40" will run 2062 rpm. @ 60 mph. To me, 136 rpm. ain't much difference. Good luck. All sounds good.

 

So a simple equation that puts you roughly in the ballpark of what gear ratio to go with based solely on tire size would be

(Stock gear ratio) × (New tire size) ÷ (Old tire Size) = New gear ratio

Example for my truck

3.73 x 35 ÷ 31.65 = 4.12

Now since I like to do a lot of crawling and have a lot of extra weight added on I opted to go with 4.56 rather than 4.10 or 4.30 for more low end torque and some giddy up.

 

I'm running 456 and like them, 488 would've worked fine for me too, most of the speed limits @ here are 60-65.

 

I’ve got 4.56 full armor with 285/75/17 and a auto, I love the way it performs I’d do 4.88 if you have plans for 35s.

 

I can't believe, as much as I've read about gearing, I've not seen this formula. Won't tell you what you need, just tell you what will get you back to where you were before the tire change. That is great. Thanks.

 

I have 35s and 4.88s. Do 4.56.

 

I have 32's with 4.10 & 2.7, auto., 4X4. Very weak puppy, straining constantly.

 

I'm Maggie supercharged w/ 2.8" pulley running 35's and 4.56 gears with light armor. Truck is a rocket

 

When figuring gearing, big difference in 2.7, auto, 2.7 MT, 4.0 auto. 4.0 MT, supercharged, not supercharged. Everything's got to be figured in.

 

6-speed with armor, 33’s and other goodies. I will be going 4.56 gears soon, even though I know I’ll be slightly over geared.

If I was the same setup with an AT, I’d most likely go with 4.88’s. YMMV.

 

So for guys running 33's with V6 Auto Trans and 4.88 gears, what is your top speed on freeway? Am I correct to think I'll have better freeway speed with 4.56?
Right now I drive 75-80 mph often! I think it would suck if I couldn't get my truck up to 75 mph.

 

I'm running 33s with 4.88 and my truck is comfortable at 60-70. I can surely go 75-80 but my rpms would be pretty darn high. At 65 I'm sitting at about 2500ish rpms. However, when there is a steep uphill grade, my truck doesnt skip a beat

 

On 33's with 4.88 auto you'll be cranking over 3000 rpms at that speed. I'm running 35's with 4.56 auto and at 70mph my rpms are at 2250

 

75 mph. on 33" with 4.88 = 2609 rpm. 75 mph. on 33" W/ 4.56 = 2438 rpm

 

OP, do you have auto or manual trans? That will make a difference in making your choice. Also, what elevation are you at? If you live at a higher elev like 5000ft and up, your motor loses more power so lower gears are better suited.

FWIW, I have 285/75/16 that I'm running 4.56 with an auto trans. Ratio seems really good to me at 5200ft elevation. I also ran 265/75/16 as well with these gears and I liked that as well. IMO, if you have an auto trans, 4.88 sounds more appropriate. If manual, then 4.56.

 

Manual and auto are different. Manuals are geared lower overall.


OP, you're kinda in the middle ground with the 295s. Your truck is a heavy girl, so I would recommend 4.88.

 

Also, check out this site for calculating: http://www.grimmjeeper.com/gears.html
A750F is the auto trans. I don't recall the code for the manual.

EDIT: RA60F is the manual trans code

 

My truck originally had 245 tires so with that math, it works out to 4.08. Seems like 4.56 would be the better choice.

 

Just keep in mind that just like @rphillips stated this equation basically just puts you in the ball park of the gearing that would bring you back to a stockish feel. With that in mind, going 4.56 like you stated with the AT I don't think you'll be upset. I have a MT on 35's and feel like I'm slightly overgeared for DD use but feels great offroad