2012 Tundra Regear questions

Hey guys! Sorry I’ve been out recently, have been focusing on local events as well as my personal life. Hope you are all doing well. Anyways I am seriously considering regearing my axle. I like my 35’s but the gas is ridiculous and the highway speeds suck I’m at 2,000 RPM at 60 mph. Realistically the 35’s has made it virtually undrivable thanks to the 5 speed transmission. I have the 4.0 V6 with the 5 speed, does anyone know what regear is available to me?

 

Anyone have any guidance?

 

I'm not aware of there being any chassis or suspension differences for the V6 (I didn't even know a V6 was an option at all honestly). So any normal regearing should be available to you. My opinion is anything besides 5.29s is pointless. The gearing will get the engine into the power and as well as increase torque at the hub so it'll drive the 35s easier, however in my experience I didn't notice any considerable mpg improvement and certainly not enough to ever pay for itself realistically. So if you're fine with the same mpg but improved power and torque then gearing is the way to go! If you mainly want better mpg you'd be better off spending that money on something else honestly.

 

First off thank you for the advice. I’m not sure if the axle is the same on the V6 as the 5.7 I believe there’s a difference but I could be completely wrong. Last I heard I don’t have many options 4.88 was the highest available. I thought it could help with mpg? I started wondering about it recently because it didn’t make sense to me lol. I mean at 60 mph I’m at 2K rpm so if a regear can help me bring that down then it would help with highway mileage, I don’t know if that how it works though so feel free to educate me!

 

Toyota doesn't have a lot of axle options, so if you don't have the 10.5" axle then you'd probably have the same axle as a 4Runner or GX (again, seems unlikely but i don't know). All Toyota axles I'm aware of have 4.88 and 5.29 options but those will increase your rpm. The higher the gear number the more rpm your engine has to spin to go the same speed, and it's a proportional change, so if you go to 4.88 and have 4.30 now then you'll spin 1.13x rpm more so that 2000rpm is now closer to 2300rpm. If you want less rpm driving around you want a numerically lower gear which I'm not aware of anyone making those (usually the OEM makes the lowest numbered gearing and everyone wants a higher number).

Running less rpm isn't the whole story though. There is a trade off of rpm and torque to the tires. If your engine is spinning a slower rpm, then there is less gear reduction (ie less torque increase) through the axle so the engine has to work harder to keep the truck moving at the same speed. You could have an engine that is at full throttle at 1500rpm to go 60mph or an engine that's idling at 2500rpm, same speed, different rpm, but one is struggling to go that fast and the other thinks it's in a drive through. In general, if an engine is idling it is able to run more timing for the spark plugs and more efficiently extract energy out of the gas. There is your trade off then: higher rpm, but less gasoline needed per revolution--or less rpm, and more gasoline needed per revolution. Which is why generally regearing doesn't pay back on mpg very well if at all.

And to dive further, the engine has an efficiency curve and making the engine spin faster makes it more efficient (this is why peak horsepower and torque are near 3500rpm). So not only would gearing to a lower number make the engine have to work harder to go the same speed, the raw horsepower and torque capability at that rpm is very low so the engine may not even be able to push the truck the speed you want at that lower rpm, meaning the engine will have to downshift to a lower gear (which is the same thing as running a higher numerical axle gearing) to be able to maintain speed---and now you'd be back to where you are now, instead of 5th gear you'd be using 4th gear though and rarely if ever have 5th gear available.

Usually people regear because 5th (or 6th) gear is no longer utilized due to the rpm in that gear being so low that the engine doesn't make enough horsepower and torque to be useful at that low rpm. Running a higher gear like a 4.88 or 5.29 increases the engine rpm so there is more horsepower and torque that can be on demand at a given speed as well as having more torque applied to the hub due to the larger gear reduction. So more torque all the time to the tires, and the engine is more in the power band when cruising so the higher transmission gears can be utilized again. If your truck is sluggish and slow to accelerate or hard to maintain speed, you want to regear. If you're looking for better mpg, it'll be a wash by regearing and certainly won't pay for itself anytime soon.

 

Thank you so much for the explanation! My issue was around 32 mph it tries to shift to 5th way too early. I fix that by manually shifting but on the highway I’m running around 2K rpm just to go 65 mph I mean I just don’t see it as realistic it would take me forever to reach Tennessee going 65, the truck drives fine but on the highway it’s incredibly inefficient. My solution may be to buy a V8 tundra on the side from what I’m seeing. I haven’t calculated MPG but I know it’s horrific I am rubbing pretty bad so maybe I’ll go down to a 34” tire won’t make much of a difference for my issues. I appreciate your participation in my curiosity and any advice is always appreciated

 

My 4.6 v8 does 1500rpm at 60mph. There's enough power to accelerate at those rpms, but v6 might struggle, hence 2,000rpm cruise? It's 270hp vs 310.

Either way you spin it(pun), it probably doesn't have enough power for low rpm highway speeds me thinks.

 

Sounds like I need a 34 to me lol. Nice pun. I’ll probably get a newer tundra or older tundra and do a more simple build maybe on 33’s max. This will be the bigger truck the work is done and I have no intentions on getting rid of it. Also not much I can do for power either