Normal RPMs without towing?

I have a new 2021 5.7 crewmax 4wd. I put a leveling kit, 20 inch wheels, and 33s. I feel like the truck is really struggling going up even moderate hills on the highway. To maintain 75mph, it has to pull 3400 rpms. Is that normal? Or do you think there is a problem? This is without towing anything. And I am in CO, so would the altitude make a difference?

 

That sounds like 4th gear. Given the altitude and your described terrain, sounds normal. When it flattens out it should shift to overdrive and drop you somewhere around 2k RPMs but you’re making way more power at 3400.

 

Yes altitude makes a considerable difference, denver you're losing around 15% power and up to like 30% or more loss at the peaks. That plus larger tires and increased cross sectional area don't help a truck that has a finicky cruise control/throttle programming to start with. Mine used to downshift all the time even if just a slight hill.

 

Yea I say normal, It's probably in 4th or 5th trying to maintain 75..

 

I'm in a relatively flat area, some hills but no mountains. 1500-1800 rpm normally, or 2000 if going a little faster.

Your mods probably had little to do with it, I have 33" tires on 20" rims as well.

 

Welcome, truthfully I doubt there is anything wrong with the truck. The addition of a leveling kit will create more drag than a stock truck. Secondly it sounds like you added aftermarket rims and larger tires presumably all-terrains. Weight and height are always going to effect torque.

The Tundra is almost a 6k pound truck...75 mph in mountains at higher elevations is going to cause high rpms. Honestly drive a little slower...

 

Thanks. Yeah you’re probably right. I need to slow down, but hard when everyone is flying by. This is my first truck where I have gone away from stock wheels/tires and suspension, so it was a bit worrisome.

 

Around 2.1k RPM on flat ground at 75mph (actual, not dash). I usually cruise at 70mph with 1.8-1.9k RPM on flat ground also. Not at high attitude like you though as I'm in San Diego.

Truck is on 40" tires with 5.29 gearing and a supercharger.

 

Yeah I definitely get it, I don’t like seeing everyone flying by me. But in the end to get respectable mpg’s and not beat up on the truck is worth it IMHO. And at least you got one of the best damn 1/2 tons on the market

 

Thanks. I do want to go supercharger eventually. When I have built up some wiggle room with the wife.

Also, love the work that the O’Keefe Music Foundation does. Especially with the Tool music.

 

I used to live in CSpgs. 3% per 1K elevation is the ROT on hp loss for NAS engines. I recently added 20” Fuel wheels and BFG KO2s and I am supercharged and hated how the truck felt. Back to stock wheels I went.

In your situation you have probably a 25% overall power loss due to elevation with taller and heavier tire.

For example: The KO2s are 57lbs ea and the stock Michelins are 44lbs...that’s 13lb increase per tire. The stock TRD 18” wheel is 31lbs...my Fuel Torques are 36lbs and they are about the lightest I could find in 20” wheels. So in my case I added about 20lbs per wheel/tire, increased the rolling resistance due to stiffer side wall and aggressive AT tread AND increased the overall tire height by 1 inch. It all doesn’t sound like much and it wouldn’t be if we were talking about a 3/4 ton diesel...but a NAS gas engine will be affected much more. Even with the S/C I could feel the engine laboring more, it ate way more fuel than it already does and the braking efficiency went down as well. Overall the wheels and tires look cool on a Tundra but in my opinion, the execution is shit.

It’s unfortunate, bit it is what it is, and it comes down to what you can live with or without.

 

Nail on the head, want stock performance...leave the truck alone. Add bigger tires, wheels, lifts. Performance and mg will suffer. You can’t have your cake and eat it too!