I own a 05 F150 Screw 5.4l 4x4. My question is should i regear to 4:56 if I run 315x70R17's even if I don't tow or race but light off road time to time and if i have to regear would it hurt the trans. to run'em about 2 to 3 months before I do regear? Thanks

 

im running my 315/70/17 with stock 3.73 gears. I have a hypertech programmer, airaid cai, and flowmaster sido, I don't know if any of those help my truck along, but I do fine with the 3.73s. I tow some, not a lot, and I offroad a decent amount. I got mine on almost a year ago. Im still looking to regear. But yeah 4.56 is what you want. Let me know if you find a good price somewhere... Im debating between a winch or gears lol... I know I'll still get stuck if I regear, but I could use the mpgs... I have a decision paradigm I have to go through before I do everything... lol...

 

I don't have the same tire size as you but you can use me as comparison. I have an 05 with 5.4 and 3:55 gear ratio. I currently am running 285/70/17. I am going to regear to 4:10 when i get a new set of tires in about a year and also bump up to a 295 tire. I do tow heavy occasionally (45hp tractor) and lot of light towing (ATVs, boats), and the occasional off road. For me, the 4:10 will get me more pulling power and not hurt my MPGs.