I have a 01 F150 4x4 Flareside 5.4L. My question is if I lift it 4" and put bigger tires on it, am I going to have to change out the stock gears in the axles? I'm I going to experience any change in take off, towing and such?

 

If you have stock 3.73 gears and get 33" tires you will probably be OK, maybe a slight performance lost but nothing to bad. For optimal performance with 33" tires 4.10 gears are recommended, with 35"s 4.56 gears are the ones you want. With any of these combinations your acceleration while towing will be about the same, maybe even better. I have a 2000 4x4 with a 5.4 and 3.55 gears. I put 33" (285/70-17) tires on my truck I also added a Flowmaster muffler, K&N Intake Kit and Superchips tuner and I get pretty good towing performance. I would like to get 4.10 gears when I can afford it though.

 

Does your truck have a lift on it? Did you have to modify the fenders if you didn't?

 

My truck does not have a lift and I did not have to do any trimming. On a stock height 97-03 4x4, 33" tall tires will fit just fine without any trimming if they are 285/70-17 or 285/75-16, basically a 33x11.5-16 or 17. If you put a wider tire on like a 305/70-16, 305/70-17 or 33x12.5-17, which are all basically a 33x12.5-16 or 17, the extra 1" of width, may cause rubbing and require some minor trimming.