okay, I have a 2000 F150 2wd w/ 5.4 and 20" wheels with 285/55's. I pull an enclosed trailer around but I also go to work an hour each way on the interstate empty. On occasions I will pull my trailer on the interstate. I currently have 3:55's, would swapping to 3:73's give me a little more power as well as better mpg?

 

dont know about better gas milage, but should be more power. And why stop at 3.73? Jump it up to 4.10 or so and you will be happer.

 

I think the consensus is that for a gear change to be worth it you should move up atleast two ratios, so atleast 4.10 gears. With 33s I would go with 4.30s or even 4.56. You wont neccessarily get worse gas milage either. I went from 3.55 to 4.56 with 35s and I actually get better gas milage because of the decrease in engine load.

 

The fact that he does two hours highway a day is a good reason not to go with 4.56s. The reason that your gas mileage went up is because with 35s and 4.56s your truck is much closer to stock RPM than it was with 35s and 3.55s. I ran 4.56s with 33s for a while, and the RPMs and gas mileage was horrible. I put on my 35s and it is pretty much back to stock. Ntm, his tires are closer to 32s than 33s, and that would just make it worse. 4.30s may be acceptable, but I would go with 4.10s unless you plan on going up in tire size again.

 

I agree...unless your trailer is REALLY heavy and you tow a LOT, in which case I'd consider 4.56.

But it sounds like you do a lot of highway miles with no trailer, so 4.10s would be good.

Don't waste your time with 3.73. It's not enought of a change for you to notice and benefit versus the cost involved.

 

Do your self a favor and go with 4.10's, You won't be disappointed!!!!

 

You can't go wrong with the 4.10's & 33's combo. Perfect, IMHO.

 

well it sounds like i should go with 4:10's. Thanks for all the input.