Hey guys,

I think I'm swaping my 3.55 to a 3.90 or 3.92. I'm going to be pulling a 18 foot car trailer so I think this would probably help out right? I got an automatic so I want to protect my tranny as much I can.

As for highway use not towing, how many more RPM's does the truck run at highway speeds? Right now I run just a tid bit over 2,000 at 70 MPH. Will it go up a whole lot more with the different rear end?

How much worse will I get for mileage you think?

Thanks alot everyone

 

3.90s will make your RPM go up about 200 at that speed as long as you keep your tire diameter constant. (assuming that you're running 31.4" tires now). This is based on assuming 2000 RPM now. As far as milage, it's a hard call as it depends on how hard your truck is working currently with that load.

 

Yeah I will still be running my stock tires. I cant remember what size they are though. 16" rim is all I could tell you without looking haha