I am trying to increase my maximum trailer weight-lb and have decided to change from a 3.55 rear axle ratio to a 3.73 or a 4.10. I want to increase from 7900 total maximum weight to allow me to tow a 5th wheel that is 7931lbs. I have a 145 wheelbase with the 5.4 triton V8 4X4 2008. I have 18 inch tires and am wondering if this is the right thing to do. If I read the user manual correctly it would bring me up to 8900 max with the 3.73 change. Any ideas would be great, my son in law said to not worry unless I experience a need to change when towing. I think 5th wheel towing has a different calculation and am not sure of it either.

 

You can't increase the max towing weight of your truck beyond what is on the sticker for the truck

 

Half ton trucks are not really suitable for 5th wheel towing. They lack enough payload capacity. An 8000 pound 5th wheel could have as much as 2000 pounds of that on the pin. That's F-350 territory.

 

Do u plan on bumping up in tire size in the future? If u do go with the 4.10s. To justify spending 1500 or so on new gears u may want to jump to at least 4.10s anyways. I would leave it as is and see how it does. I have the 3.55s with larger than stock tires(32.8), and tow a 5000 pound tt and haul a dirtbike and 4 wheeler in the bed. It is not overly impressive, but gets the job done. I added rear air bags. U may want to as well if u do end up with a fifth wheel. It doesn't change your payload, but definitely helps with the squat.