4.88 or 5.29

A small batch was released early

 

Had 'em installed a couple weeks ago.

 

So at 65 mph today with no wind (tail or head) my 2002 Tundra 4WD SR5 V8 (4 speed original transmission) with 285/75/r16’s (Michelin Defenders) her RPM’s were 2100 on flat asphalt pavement.

Pretty good for stock 3.91 gears per the above chart? Assuming the 285/75/r16 equals 32.5” tire?

 

the chart is based on 1:1 transmission ratio. for the 1st one 4 speed, that means closer to 3rd gear.

Edit: also, that seems like a pretty high RPM for those tires at that speed. is that actual speed, or indicated speed? your speedo will be a few MPG off by running that size tire.

my dad's truck with stock 3.91s and stock size tires runs about 2k-2100 at 65 actual MPH

mine with stock size and 4.10s runs about 2k at 60MPH

 

Indicated speed. So, factoring in the delta for bigger tires my ACTUAL speed would be about 70mph+/-?

Your dads stock tires and my bigger tires are running about the same RPM.

 

Went back and did the math and this is what the site says.

 

Those charts aren’t useful for overdrive transmissions as noted.

They do not account for the increase in air that our lifted trucks are pushing. That and the weight of big tires is a big deal

 

I’ll try running the engine without O/D tomorrow to see what the RPM’s will read at 65 (actual 70+/-). I’m guessing another 200 rpm higher, but we’ll see.

 

The Toyota 4.30 are closest to stock with 285/75 tires, if just chasing a matched RPM at any given speed. They're really expensive.

 

Good info. Just wrapping my head around the mathatical part of the mechanics write now. I take peoples advise seriously and from guys like you and some others I trust here I know the higher gears like 4.56 and the 4.88 are the best call based on real experience.

 

Similar to gas mileage, there are a lot of variables to consider. Most guys regear with off road in mind, they tend to have really heavy tires to compensate for. That's where going a bit over becomes beneficial. If you plan to run a more highway style of tire I wouldn't venture into 4.88 land.

 

Perfect match, but the cost difference over a 4.56 set isn’t worth it

 

That's why I went with 4.56.

 

Seeing the Nitro 4.56 Complete Set around $1000 for the 02’ Tundra (4wd).

 

Well i just order Yukon 4.88 and got 35" tires installed. Now I just have to wait 1 week until the parts come in so it can get it installed.

 

You doing the install?

 

You’re gonna love the power

 

+5% for automatic transmission slippage. For an accurate determination of tire size, always measure the 'static loaded radius'. Measure from the axle centerline to the ground. This is the leverage your engine is working against. Then x2 as stated above.

 

I'm going to have the shop where I bought the kit install it. Just going to take them the 3rd member. They seem pretty knowledgeable out this. He used the same formula Bestgen showed.

 

Take pics! Have the shop take pics, too. Lets see all those part numbers and boxes.

 

How Are the 5.29's? What tire size are you running with them?

 

I'm running 35s. The tires are too small for the gears IMO. I may have an excuse to go to 37s since I just destroyed a tire wheeling this weekend. But, going to a 37 is opening another can of worms clearance wise but it's been the plan for a while.

 

I'm running a 34.2" tire and I'm trying to get real world experience from the 5.29's. I've talked to a bunch of people, ( experienced in the field) and they lean towards the 5.29 vs the 4.88. I just want to do this once. I will up the tire to a 35 when these wear out but not going any bigger. I don't off-road, and I drive 90% back roads (under 50mph) so when do the 5.29's feel too low? Thanks for any input!

 

When starting from a stop I need to have a delicate foot, it'll spin the 35s with ease. This wouldn't be ideal in snow country. I'm turning 2,400 rpms on the highway when my buddies are turning 2,000, same tires stock gears vs 5.29.
5.13 would be the same as stock with a 37" tire. So, 5.29 is compensating for the tire weight as well as size.
It's just my opinion based on my limited experience but, for the road, with a 35" tire I would opt for the 4.88 ratio. I don't have any experience with the 4.88 and I really wish I did.

 

reasonable price? i haven't checked with them yet.

 

It would be nice to be able to try each one to find which one you like best, before committing. It’s easy for others to say they like it and then take their word for it. But we all have different preferences for what we think it should feel like.

 

They quoted me $1650ish for labor and oil. I ended up scheduling with RSG though for $1800ish. These get put on March 27th

 

This is so true. Everyone's gonna have a different idea about what they want. I didn't like that my truck couldn't hold 6th gear on the highway with stock gears and 35s. I felt the engine and tranny were working harder than necessary. But, I'm not sure how well it would hold 6th with 35s and 4.88s. It certainly holds 6th with the 5.29s. If I were towing a trailer all the time 5.29 with 35s would be great.
It's my opinion that stock the truck's ratio was good, held 6th and got descent mileage. So, I'd be happy returning to something closer to stock.