Hello all, I have a 99f150 orp and i just put a set of 285x70x17 on it. I can tell I have lost some power going up steep hills, don't seem to be as bad on flat ground.I have the 4.6 and I put the K/N fipk on it. I need to know if the gear change will give me my power back and mabe even a little more I hope. Where would the best place to buys the gears from and how hard of a job would it be to change. I'm also thinking of a chip to. I appreciate the help.

 

My truck is similar to yours. I run the 33x12.50 tires, had the 3.55 (4.6 engine), and my only engine mod is a K&N.

Anyway, it did more than just give back the power, the truck now scoots in 1st and 2nd gear. It made a big difference. The RPMs are only a few hundred RPM higher and I never notice it anyway.