I have a 2001 screw that has been lifted and has 35 inch tires i do a little city driving and some highway and pull a trailer. I have the 5.4. would it be better to go with 4.10 or 4.56. I have the 3.55ls right now and getting 16 mpg would this improve.

 

if you search there's a thread somewhere on here, maybe in the tire or transmission forum that says a good rule of thumb is something like .11 or .12 times your tire diameter which would put you closer to the 4.10 you will get better mileage with the 4.10 but the 4.56 will feel "torquier" I'm no mechanical genius but this is just what I've gathered from what I've read on here, try to find that other post about regearing. hope this helps

 

If you're towing somewhat consistently, I would definitely go with 4.56s. I'm running 4.56s with my 33s right now and I never tow and I'm very happy with them. The RPMs on the highway are a little excessive though. The other day I loaded ~1200lbs into the bed of my truck and she still got up and moved better than she ever did with 3.55s.

 

I spoke to a gear guru, he stated the 4.10 is a great gear for clos to stock with a little more torque than stock, and the 4.56 is for toteing the note and if you romp on it the 5.4 could twist some stuff, the closest gear to stock is 3.86 with the 35" tire, Im in the same truck 01 F150 4x4 lariat 3.55 stock gears with 35" tires, have;nt diven the truck yet..But with all the hopups you have Kicker 33 and feel the strain I know I will as well, Im thinking of going 4.10, I want a good gas gear as well, the most I might pull is 3,000lbs, a enclosed trailer with a bunch of toys init..up and down the hi-way..

 

Liquid 1
i can only feel it in town when on the gas hard and pulling my trailers but not that bad