I just bought a2008 f 150 4x4 short bed with 3.73s it only has 10k miles on it.Per the manuel it should tow 9000 pounds. It has the dealer instsalled cal concepts kit which the put 35s on it, I went to tow my 5800 pound boat and NO power at all it really sucked. I went from a 2wd ram 2005 1500 with a cold air and programmer with 35s and it towed like a champ. Are fords really this weak? Is ther somthing very wrong? or does the cold ar and the programmermake that big of a difference? I already took to dealer and they flashed the transmission they said id get a lil better gas milage, but im still onlygetting about 12 mpg. please help

 

Which engine do you have?

 

5.4 triton 3.73 gears 35 inch tires 4x4

 

ANY truck running 35 inch tall tires with only 3.73's won't pull as hard as a truck with stock-sized tires. Sounds like you need a ratio swap, to 4.10's or something even lower. My truck's tow rating is 9,300 pounds (stock tire size) and my travel trailer is 7,000 - I have power to spare and never struggle.

I'd also be very happy with 12mpg's on a 4x4 truck with 35's.

 

The only problem im having to under stand is how could my 2wd ram 1500 with the same 35s and 3.55 tow like a champ? the only difference was the dodge had a programer and cold air intake i really cant see it making that big of a difference but my ram would jam like you wouldnt believe?

 

all the 4x4 parts add probably 400 to 600 pounds to the truck vs. a 4x2. Even if 4x4 isn't engaged, you're still having to cart all that 4x4 stuff around, and the transfer case etc. adds a parasitic power loss...

 

I have a 04 5.4L FX4 with 3.73's, also have Edge programmer, Airaid intake, custom exhaust, 325/60/18 Nitto TG (33X13X18) I tow our 5000lb camper every other weekend and usually one of our S185 Bobcats (7000lbs with trailer) 2-3 times a month, and my truck doesn't lack for power at all. For a 1/2 ton it tows very good, actually better than a Chev 1500HD 6.0L that we use to have at work.

 

Going from 30" diameter tires to 35's is a 16.7% increase in OD. It will have the same effect as keeping the stock tires and regearing the diff from 3.73 to 3.11. Not gonna be very gutsy with a road gear in it.

If you want to restore factory performance you're going to have to regear. In your case it that works out to a 4.30 rear diff ratio.

Brad

 

I've towed around a car trailer, which is about 5000lbs with the S4 in it, and never seemed to notice any problems. Even got 14MPG doing it. My truck is completely stock with the factory 20's. Not sure on my gearing thou.

 

I had a pallet of concrete blocks sin mine this weekend. Fork lift operator at Lowes estimated the pallet at 1500 lbs. The rear was squatting pretty low. I was surprised the truck had no problem. I babied it because I didn't want to damage anything, she was slow up hill on the ramp, but level driving was easy. If it weren't the the rear squat, I might not have known that I had that much weight in the back.

 

Programmers are a Godsend for the 5.4L

 

I've got an 05 supercrew with 35's with same gears as you and pull a tractor in the 7,000lb range. Believe me it isn't fun, but it will handle it. Im at the verge of needing a f250. Should handle it without much trouble. I get around 9mpg if not less.

 

Thanks so much it seems like ill be needing a programmer and cold air intake any suggestions?

 

check out vmp's set up as well as power hungry performance's (but just be prepared for the wait time on custom tunes for php)....the 5.4 doesnt seem to REALLY benefit from an intake, but programmers make the truck drive a whole heck of a lot better. i tow my 7000lb boat with out too much issue about 230 miles to the lake all summer long.

 

Im running 34s on my truck and 3.73s. My truck tows like crazy and gets 17-18 mpg. Intake exhaust and custom tuned gryphon!!! Makes a hug difference. As far as waiting for tunes its well worth it. Only took about 3 weeks for my 2 tunes.