05 Tundra gear change - increased towing capacity?

My 2005 Tundra Double Cab 4x4 with 3.92:1 axle ratio has maximum tow capacity of 6,800 lbs. My travel trailer (fully loaded) is close to this weight, and the truck struggles pulling up the hills.

Ford and Chevy both publish increased tow capacity with lower gearing (higher ratios):

Ford F-150 (5.0L) 3.55 axles has 7,700 lb tow capacity
Ford F-150 (5.0L) 3.73 axles has 9,300 lb tow capacity
Silverado 1500 (5.3L) 3.08 axles has 6,700 lb tow capacity
Silverado 1500 (5.3L) 3.42 axles has 9,500 lb tow capacity​

Has anyone changed ring and pinion gear ratios in their Tundra to increase towing capability? Toyota does not publish towing data to verify this. I realize that MPG would decrease slightly during non-towing.

I increased my tire size from 265/65R17 (30.6") to 265/70/R17(31.6"), which is -3.3% revolutions/mile. So I would need to change gearing to approximately 4.10:1 just to account for the increased tire size only. But if I changed gearing further to perhaps 4.56:1 would that increase my towing performance?

 

Sounds like you might be confusing capacity and performance.

It's kind of like having a plastic 5 gallon pail and a steel 5 gallon pail and thinking that with the steel pail you can fill it with more than 5 gallons. Sorta. It reads strange though. lol

 

Better gearing will probably help with hill pulling for a particular load, at the expense of fuel economy and top speed. However, don't assume you can now pull or carry more weight. Not only does that put and potential insurance settlement at risk, but also makes you potentially liable for injuries to other people, in the event of an accident while towing.

There are also other factors that help determine tow capacity, such as engine power, tires, brakes, and suspension. So no, it won't increase your tow capacity but may make handling of your existing capacity easier and more comfortable.

 

6800lbs is a struggle for the first gen tundras no matter what. I pull a 31' sportsman that weighs 5900 dry and it struggles with the hills too. Lot of weight and drag. I always say if you're wanting it to pull easier, get a diesel that's built to pull heavy loads with ease

 

Agreed. I wouldn't increase the trailer size or weight above the rated tow capacity of 6,800 lbs. But was curious if better gearing could help with pulling the mountain grades, and if anybody else has tried it.