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As the title states, I'm considering new tires for my 94 F150 351w E4OD (3.55 gear ratio). I bought it with a 4" lift already installed, and the current 31X10.5's look a little small to me. After reading some other posts, it sounds like there are other things to consider when increasing tire size such as recalibrating the PSOM and potentially re-gearing?
Does anyone have experience with a 3.55 gear ratio, lift, and 33X10.5 combination? What are your thoughts with that combination and a 3.55 ratio? Do I need to consider anything else when increasing tire size? This is my daily driver. Although most of my driving is back country, I need it to drive well on the interstate occasionally. Thanks for any and all input!
I don't really need the ground clearance. Couple hunting trails is about as rugged/off-road as I plan on getting. Its more visual at this point given I bought the truck with the lift already installed.
For a 4 inch lift I would go with 33 12.50. As for the 3.55 gearing it will be better with something like at least 3.73 or 4.10 but at least you have the 351 which makes more low end torque than a 302 does. With the 351 it will not have as much issue with larger tires.
Years ago when more of these trucks were daily drivers I knew a lot of guys running 33s with that size lift on otherwise stock F150s and Broncos and it was fine. I would at least go with 32 11.50.
Basically what I'm saying is that if my truck was a 4wd and a 351, I would have a 4 inch lift and 33s. But since it is a 2wd with a 302 it will keep its leveling coils and 31s.
Keep those Alcoas though.
Reprogramming the PSOM is easy to do, but you have a limited number of tries to set a new variable. I think the limit is 10. The speedometer only cares about tire size and not gearing like older vehicles.
The front of your truck does look like it has radius arm drop brackets etc and seems to be a 4 inch lift. But the rear looks a little low. Does it have blocks or different rear springs? The 4wd trucks came factory with a 1.5 or 2 inch rear block with wings on them.
Personally I would ditch the lift and run the 31's. But that is just me.
If you like the lift I would run the smallest tire you think doesn't look stupid. It will reduce your cash outlay and reduce the added wear tear. It will also reduce the modifications you might need to live with the taller tires.
The bigger the tire you run the more you crack open pandora's box.
33" and 3.55:1 should do about 2400rpm at 65mph in third gear, just use that unless you have to go faster. I always felt these trucks were under geared from the factory.
I would regear, 4.56:1. The tires will not only be taller, but also heavier...and have a bit of head room if you ever wanted 35s. City economy would easily go up some, freeway would probably be a wash but you could then get out of your own way and actually tow something if needed.
33" and 3.55:1 should do about 2400rpm at 65mph in third gear, just use that unless you have to go faster. I always felt these trucks were under geared from the factory.
I would regear, 4.56:1. The tires will not only be taller, but also heavier...and have a bit of head room if you ever wanted 35s. City economy would easily go up some, freeway would probably be a wash but you could then get out of your own way and actually tow something if needed.
IMO, current setup looks fine to me.
Even with my 31s and 3.73s I leave OD off unless I'm going over 50-55. I don't know why Ford originally set these trucks up to shift into high gear at 43-40 mph. Especially since like you say they were geared as if they didn't even have OD with 3.55 being the best stock option.
Actually both city and highway economy will be reduced. Ever time you stop the bigger tire has to start moving again. This is why I tell people to avoid 6 inch and 35s. The mpg loss will not be that much esp on a 5.8.
I would definitely consider regearing to 4.10 gears eventually. I would do the 4.56 for a 302 but not a 5.8 unless it had 35s.
Taking the lift off could be an option too. But I'd keep it.
I have a 93 5.0 e4od and literally just put bf all terrain Ko2 33x1.5x15. They’re awesome and I love the look. I programmed my psom today based off a super helpful video on YouTube it’s called p’ing the psom. You have to hit the select
button like 100 times to get to the correct conversion for the larger tire. Don’t blast that button like you’re blasting your prom date. I broke the plastic arm that pushes the button on the psom… so now I gotta go to the pull and pay and find a new gauge. Be gentle, especially if it’s cold out. It’s 30 year old plastic. I noticed an improvement in shifting because the tires that were on there were 31s which was not the stock tire size.
Thanks everyone for the input! Sounds like I could go 33X12.5 without absolutely needing to re-gear but I should consider it. Will follow back if anything is worth reporting after the changes.
As a side question - does anyone know how to tell the number of ring teeth I need to use in the PSOM recalculation formula? Conversion constant = RevPerMile X ToneRingTeeth / 8000
My 95 F150 4x4 has the 351 and auto trans. I've installed BFG KO2 33/10.50x15 on stock Alcoa wheels with stock suspension. Had to trim about 1/2" off front bumper ends and all is good. Ran stock 3.55 gearing and it seemed to be just fine. Decided for towing my boat I needed 4.10's and installed them this past September, Now it seems the truck is far better then it's ever been in acceleration, driving and can see no real change in economy.
That’s weird I have the exact same setup in an extended cab but with a 5.0 and have net had to trim anything. Is changing the heating hard? Do you have to put on a whole new rear axle?
I didn’t know that. I was able to get the 10.5 in the Ko2. Discount matched Costco and I saved like 100 bucks. I think I was out the door for under 1,200
