The 4.88 mega thread!!

Okay thanks! I had no idea that was even a thing.

 

if you're AT, just go 5.29 and future proof it. I said I'd never go bigger than stock now I'm trying to fit 35s in my shit lol

 

I sometimes drive from Florida to Texas. That would be some hella high RPM's for stock.

 

I got a calculator on my wall in the garage.

 

You will be surprised that its not 5.29 are only a couple hundred more than 4.88

 

http://www.grimmjeeper.com/gears.html

Once you input the numbers they stick until you change them.

 

If you run up to 33’s keep it 4.88 unless you have crazy amounts of weight. If bigger than 33’s than 5.29. Simple rule

I run a true 32” (255/75/r17) and today with a 110 miles round trip netted me 19.7 mpg avg. not bad. My truck weighs 5,610lbs on the daily

 

How did your MPG's differ from the stock 3.90's and the 4.88's?

 

About the same when I had the stock tire size with 3.91s. As soon as I went up a size in tire I could never get better than 16.5 on stock 3.91’s. The 4.88’s allow the momentum of the truck to hold its weight and speed better which requires less work...for basic driving this helps “sip” fuel more optimal...(thanks OVtune) This leads to less fuel consumption especially 65mph or less. OVtune helps bring it back to stock like mpgs with a whole hell of a lot better truck driving experience with more consistent behavior and power.

 

How about 65+ mph? I drive 65-75+ regularly and wouldn't want mpg to suffer at higher speeds.
I plan on sticking to stock, or slightly larger than stock tires. I'm also running OvTune.
At 80, my rpm is 2000. I calculated with 4.88's, my rpm @ 80 would be ~2500.

 

It will suffer a bit because smaller tires will consistently spin higher rpms. For this reason I went a taller, lightweight tire with 1/2” skinner width. The speed on the 84 in Idaho is 80mph. With stock tires I imagine it would be fun as heck to drive with stock tires, but cruising above 65 likely won’t see better than 15mpg IMO (especially not in CC)

 

Jesus Christ! Maybe I'm just better off sticking with the stock gears. Where I drive it's fairly flat, here in Florida.
You think there would be that much of a mpg difference between 2000 vs 2500 rpm @ 80? I figured it wouldn't be too drastic considering with 4.88's, the engine isn't having to work as hard to spin the tires.

 

That 500 rpm gap is the sweet spot for cruising with 4.88’s unfortunately. My 75mph is 2300 rpms giver we take a few with 4.88’s and my fuel bar sits 1/8-1/4” higher which equates to 4mpgs from my math than it did with smaller tires at that speed with the same gears. These trucks are the sensitive type unfortunately. I do love the setup for my truck. It’s super fun in all terrains.

 

"Sweet spot" as in a positive or negative way? It sound like negative. You're telling me that if I slap some 4.88's on my completely stock truck, I'll get 4 MPG's less??
Also, could you elaborate more on the fuel bar thing?

 

At that high speed, 75+ yes. I think you would achieve worse fuel efficiency

 

Hi there. Sorry to steal the thread here, but just curious, did you do the OVTune somewhere in Oregon? I'm an Oregonian and really want to get this done, but don't have a PC and really don't trust myself one bit when it comes to anything more sophisticated than pressing my "start" button. I'm exaggerating. But you get the point. Any help is appreciated. Thank you.

 

What’s everyone’s impression on using OvTune with the regear? I love how it drives with just the new gears. Is the tune needed going to make it more enjoyable?

 

Yes. STILL REQUIRED. You will see.

 

Elaborate more please

 

AT or MT?

Either way to get the proper power out of the engine, to the ground much quicker the tune is required. No delay, no rev hang, no balking. Yes the gears are nice but the engine needs tuning to make the most torque and make it lower in the RPM band.