4.88 or 5.29

Even though 5.29’s are “too low” for 35s. I wonder if someone like me who does 95% city commuting would see a mpg decrease vs 4.88s. A few extra rpms just don’t seem to bother our engines. But too few rpms definitely bogs down efficiencies

Warren are you able to estimate mpg of 5.29 compared to the 4.30s yet?

 

Well, yes and no. I put just over 1,000 mi on this weekend. On the way to Mojave, bit of a head wind, I averaged somewhere in the 10-11 range. On the way home, driving a little slower and with a shorter stretch of headwind, the computer says 12.8. I've noticed there's a huge difference in mpg between 70 and 75+. I was closer to the 75+ on the way there and closer to 70 on the way home. So, if my calcs are correct, 12.8 mpg is actually closer to 13.8. That's given that a 305 70 r18 is 8.5% larger than the stock 275 65 r18.

 

Yeah the wind signature of our truck is so big, especially when youre lifted and wider as you are. Im sure that does more damage to mpg than the rpms.

Im on stock tires lifted 2 inches. My mpg goes down from 17 to 14 if i go above 70

 

Yeah, that's what I've experienced, above 70 = no bueno. I really don't need to go that fast..........on the road.
Lifted Tundra aerodynamic profile:

 

There for a sec I had to double check I was in the first gen page...

 

Sorry, I've got a 3rd gen. Thanks for pointing out my error.

 

2006 double cab 4x4
35” tires=4.88
37” tires=5.29


(30” tires=3.92 stock ratio)

first gen v8’s are turning somewhere around 2100-2200 rpm (give or take) at 70mph on stock tires.

 

Its not that hard to clear 37s with LT. You need upper heims, push the lowers all the way forward and do the alignment with the uppers. That will clear the rear of your fenderwell and you won't have to do a body mount chop. Then, take a bottle jack and wood and bend/push the inner fender up about 2".

 

Where in this particular area of the inner fender you're referring too? Curious on that part.

 

Thanks Alex. I'm having problems with too much camber and a lack of good alignment techs in this area. So, I might have to upgrade to heims. The 37s should arrive today.
You're going to T2S I hope?

 

The pinch weld gets "folded" over and the top of the inner fender gets moved up. It was helpful to actually "see" what Alex did. So, you'll have to hook up with him for a run

 

The metal part of the inner fenders. When you install long travel you have to ditch the plastic.

Yeah I'll be there Wed - Sun. Let me know when you install the 37s. I'm currently debating with myself 4.88 vs 5.29...

 

There's those pesky 2nd/3rd gen guys again, hijacking our little first gen discussions.

 

Time for your not a first gen meme!

 

All this info and still I have one question...who can just make this decision for me? 2017 crewmax going up to 37’s, putting in lockers, should I regear and if so 4.88 or 5.29? I almost never tow, I drove mostly highway 80+mph, I will likely supercharge in next year. 4.88 seems plenty to me, but am I missing something? Will be breaking lose all the time after I supercharge? Aside from all the times I am doing it on purpose?

 

If it were me, I’d do 4.88. I went 5.29 mainly because I tow a heavy trailer and needed to be as close to stock as I could with my 37’s, plus I live at a high elevation

 

I'm putting 5.29's on in the next few weeks. My tires are ~ 34" (275/65/20) I drive mostly back roads and tow occasionally. I went back and forth on this many times, but in the end I want it to make a difference that is purposeful, and noticable on a daily basis. I've added a lot of weight with sliders, bedliner, rack, TONS of sound deadener, and gear. As it is stock, I never use 6th gear (even on the highway it won't stay in 6th for anything other than downhill) so...
4.88's would be back to stock, but with the additional weight of mods and tires, the 5.29's were unanimously recommended by 5 different, unbiased, professional opinions, whom had no hesitation to go with the taller gear, and explain why. The answer is: You are simply putting the truck into it's powerband 100% of the time, and the transmission is happiest when it's in the powerband.

In the end it is roughly 400-500rpms different from stock... for the 5.29's

 

And just like that I’m torn again Lolololol...ok question, on 5.29 running 95 mph will it love it or be screaming rpms? Real world scenario here

 

If you really drive 95mph, go with the 4.88's. I'm under 55mph 90% of the time I drive...

 

I hang around 85-90 when traffic opens up. If the 4.88 are better for top end that helps a ton

 

4.88 are the way to go for those speeds. You 6th gear is .58 overdrive... You'll be fine.

 

According to calculators, stock is almost dead nuts the same as 37s and 4.88s.

This of course doesn’t account for the weight of the tires/mods and the significant wind drag added when the truck gets taller and taller.

5.29s with 35s sounded good to me at first, but it is considerably more rpms than stock for every given speed

 

They're back! Get outta the first gen section with your behemoths and what not!

 

Didn’t even realize this was in 1st gen section, it was best thread i could find for a gear comparison. I haven’t seen a good first gen running around in a while, any of y’all in middle tn?

 

Wow im terrible too

 

Guys, guys

 

Epic.

 

I did the math, purely on diameter, the diff's gears should be about 4.93 to get back to original power band. Of course this doesn't account for added load such as mass of the tires, added rig weight and rolling resistance. If you are going 37's, then go with 5.29. If you are going with 35's, stay with 4.88. In my opinion, 5.13 is ideal for mpg, performance and top end, but no one makes it for our truck.

 

5.29 gears installed. Just noticed the truck stalls (feels like I’m hitting the speed governor) when the speedo shows 90mph. I recreated the failure a few times now. Spoke to Keith from DirtyDeeds and pulled the ABSII fuse and the problem seems to go away. Trying to figure out what to do from here. Has anyone come across this issue? I have a 2010 Tundra Dbl cab 4x4.