Thoughts on 4.88 vs 5.29 longevity

Yeah you have a good point. To my knowledge, our trucks come with a 4.30 ratio from the factory with Michelin LTX AT 275/65R18 which are exactly 32.1" in diameter. I haven't seen much about our "adaptive ECU". The computer can basically detect a change and adjust accordingly automatically?

 

You need to stop looking at charts Ginny real life. The charts don’t take into account the way your ecu reacts to the wheel speed being slower in relation to the throttle position. The extra load of the bigger tires causes your ecu to pull timing and add fuel. This equates to a 40hp loss. That’s not from the tires. The chart won’t help with that LOL.

when experts give advice it’s not for kicks and giggles.

 

The adjustment it makes from bigger tires equates to a loss of a massive amount of horsepower. You’re over analyzing this. You want 5.29

 

I’m out. Can’t take it anymore. LOL.

 

Haha. All good man. I don't intend to negate or ignore your advice, experience, or expertise (which I'm positive is way more than I could ever have). I just want to be sure I'm making the right decision for my use case. This particular change is a significant investment and getting it wrong could be very costly which is why I'm here asking all the questions I can before I jump in.

 

You can't get much better advice than what Keith gave you.

 

That's a generic and outdated chart for 4 speed transmissions.

Yes, simple math suggests 4.88 to bring your speedometer back to the same as factory, but you still have the added rotating weight of the larger tires. Go 5.29 if you are going through all of the work to change gear sets. It will tow better, shift less on the highway, and the fuel mileage wont be any worse than stock gearing with 35s.

 

Yup. I think i'm gonna go with 5.29. Was just looking to reconcile some of that other info first. Now i have to find a good reputable installer in my area. SDHQ quoted me $5,200 parts and labor (which includes the 500 mile break-in work). They also said they'd need my truck for a whole week. I knew this wouldnt be cheap but $3K+ in labor and 1 week lead-time seems a bit crazy!

 

SDHQ is for rich folk.

Keep lookin' lol.

 

Geez. I spent $5200 on 4.88’s, rear Detroit locker, front true trac, fluid, and installed in my 1 ton axles. Last I checked you could get the 5.29’s and a rear auburn for the tundra for like $1500.

 

@dirtydeeds - you can come back now. LOL

 

For that sdhq price I would have Keith do the installation in San Diego. Have him keep and drive your truck the 500 miles and pick it up and go home.
When I do gears at some point I am going to have Keith do it, even tho there are places within a few miles of me that can do it for a 1/3 the price.

 

I would contact Erick at State 48 Overland about the gears and Ben at Toy Pros in Mesa for the install. They are in the same building and are both great to work with

Toy Pros
63 E McKellips Rd, Unit 123, AZ 85201
(480)687-4118

These numbers are not 100% accurate because it is from me looking down at my dash looking at an analog tachometer while driving in the sun trying to miss the glare. These are close numbers, I have 5.29’s running 35’s:
MPH RPM
70 2175
75 2375
80 2400
85 2600

If you do the math the numbers are off but again, from the drivers seat.

I have had these gears for over 3 years and I have no complaints

 

bored so I made some actually useful engine rpm charts. Doesn't account for tire squish on the diameter but it should be close-ish

 

Thank you!

 

I’m pretty torn on this as well. I just sold a Jeep on 37’s with 4.88’s that couldn’t do above 70 on the freeway. Super fun around town, but just revved way too high on the freeway (Note: not suggesting 37’s/4.88’s on a wrangler says anything about tundras, just relating a vehicle that was geared lower than I enjoyed).

Most of my driving is freeway, and I want this to act same as factory with my 35’s, not trying to win drag races off the line at stoplights. It’s seems 4.88 and 35’s should be close to factory driving experience. People wanting improved performance/power vs factory should do 5.29’s on 35’s.

@dirtydeeds, are you saying that 4.88’s and 35’s (285/75r18) will perform WORSE than factory gears/tires? If so I will go 5.29. I don’t believe any charts or theories, I only care about real world experience, and yours and others is appreciated

 

He's gonna tell you to go 5.29s

 

Keith only recommends 4.88 if you will never go above a 33.5 inch tire and don't have a ton of added weight.

 

Yeah, I understand the message of “these trucks handle 5.29’s just fine, there’s no downside, only upside. Why wouldn’t you want all that free extra power?!”

But that’s not really my question. It’s a direct comparison to stock performance. If people who have done 4.88’s and 35’s tell me it actually performs worse than factory gears and tires, then I’m convinced. But for those who think higher RPM’s are totally worth the extra power, that becomes a personal preference, and I want to separate that from objective performance vs factory spec. Not sure I’m going to get it though…

 

What RPMs do you get going 75?

 

On 35’s and stock gearing it’s pretty low. I was just looking a couple of days ago and thinking about it, should have grabbed a photo. On the flat 6th gear is fine, but any incline on the freeway and it just hangs in 5th. But I tossed stock tires on a couple of weeks ago for kicks and giggles, and was loving the balance of zip around town and comfortable freeway driving. That’s my target. Not really interested in changing that balance up. Seems like before 5.29’s were available 4.88’s were happening and people were reporting stock-like performance on the forums. But maybe they didn’t know what they were missing?

My Jeep was 3000 rpm’s at 70, that was so annoying to drive long distances.

 

I cruise at 75-80mph at around 2200 RPM

 

What’s your setup?

 

About the same for me. Got 5.29s installed on Monday and couldn't be more pleased on the highway or around town.

 

Currently on 35s and Nitro 5.29s. I wanna bump it to 37s or 38s.

 

Hell yeah!

 

Texasrho83, who did your install? I'm in Alvin

 

So I was having the same fight in 4.88 vs 5.29 and the smaller ring and pinion breaking.

ultimately two things moved me to 5.29s.

Cruzr and the build for the rubicon is on 40s, dual locked arbs and hasn’t broken 5.29s.

dirty deeds insistence on 5.29s

the shop that did my install said 4.88s and the the other shop I asked said I’d hate 5.29s.

ultimately I am estatic with the 5.29s and so glad I listened to dirty deeds.

I asked about gear whine and 5.29s the shop that did install said if there’s whine it’s not done 100% correct in their opinion. I don’t hear any whine but I am partially deaf.

 

34’s and 5.29’s and would happily do it again. No whine either.