35's and 3.55's
 

How is this combo going to be on my 2007 FX4SC. I've presently got the stock 275/55/20's and want to go up to a 325/60/20 or 35x12.50's. I'm fully planning to purchase a tuner at the same time, still trying to decide which one. I don't find the power right now to be anything earth shattering, I was hoping the tuner will wake it up, but hoping the 35's won't suck the life back out of it. I've looked at endless photos of 33's and 35's on trucks like mine and really prefer the 35's. I just don't want to have to put out another $1000 for gears afterwards.

Thoughts?

the tuner will wake it up, but i think the 35's would take any gain away and probably make it slower than stock even with the chip. i also think 35's and 3.55's may be pushing it. It'll work for a while, but those tires are really gonna strain ur transmission. You wont be able to use your truck for much of a truck either, as your towing and heavy hauling capabilities will go down the toilet with all the torque your going to lose. Ive got 33 duratracs on my 04 fx4 screw with the 5.4, 3.73's, and edge chip. and i certainly can feel the difference from the tire weight. However if you dont really plan to use your truck for much more than an average daily driver and dont plan on pushing it to hard then you could probably get away with it.

I have 35s with 3.73s and custom tuning from Troyer, and on flat land its perfectly fine but as soon as you hit any hills it becomes gutless and the transmission starts searching for gears a lot. With 3.55s and 35s it is going to be dropping out of OD a lot to keep speed when you are on the highway. Also, it will stick in 2nd and 3rd gear a lot longer when accelerating which will reduce your mileage ontop of the lost mileage for the heavier tires.

Unless you can budget for gears, I'd maybe get 33s until you can afford the gears and then step up to 35s.

I run 35's with my 3:55's/5.4 and added the gryphon with custom tunes and a cold air intake, and am getting about 14 city and 17 highway. I was running it without a tuner for a while and the shift points were way off and it felt sluggish but now with the custom tunes it runs awesome, I would say its very noticeable how much quicker it is now with the 35's and the tuner than stock, the truck just drives so much better with a tuner anyways. Also my tranny temp never really jumped with the 35's either, I have always been pretty steady at 140. I say go for it, just get custom tunes cause they really make a huge difference compared to the stock tunes.

^^so you're saying that with 35's and a Gryphon custom tune it's quicker than no tune and stock tires?

What gears are recommended for 35" tires?

4.10 or 4.56's. Most will opt for the 4.56's to justify the cost and regain the acceleration.

I have 3:55's with 35's and my tranny took a dump at 60000. I am planning on gears. I also have an edge. I would say that with the tuner and the 35's it is as fast as it was with stock tires and stock tune. It also depends on the wheels and tires, as chrome wheels are heavier than aluminum. I would highly recommend gears if not right away, somewhere in the near future.

Thanks for the replies. If it's the same as stock tires and stock tune I can live with it. I'll be sticking with the stock FX4 20" rims. It's my daily driver, and I have a 30 mile highway commute to and from work every day. I'm pretty easy on the truck for 99% of the time so I'm hoping I won't have any tranny issues.

Most opt for 4.56, which is roughly equivalent to the OEM 235/75R17 with 3.73s.

If you are going to open your diffs to drop gears in, throw limited slips or lockers in at the same time. No sense in resetting gears twice you know....

Do note, however, that 4.56's will run you at higher RPM's at highway speeds..

So would the 4.10s be better if you are going to run at highway speeds?

I'm with mSaLL150. I also had 35s with 3.73s that came with the truck. Charging up hills sucked, reaching freeway speed sucked, and it seemed like the tranny was having a hard time. You will be fine if you don't push it like some of the guys on here say but you are gonna get real tired of how sluggish the truck will perform. This goes out for everyone running bigger tires but stock gears like 3.56s, 3.73s, or whatever. Your trucks may perform fine or awesome but try throwing in some gears that compliment the increased tire size and you may reconsidered how well your truck was performing. I can only imagine that with 3.56s the truck would perform even worse. I have had many power mods done and still wasn't happy with performance. I ran the 35's with 3.73s for about a year and now. I switched to 37s and yukon 4.88s front and back and the truck runs a whole lot better, but because I neglected to upgrade my gears for so long my transmission isn't up to par and Ill have to have it rebuilt/upgraded soon. The real question is, "Is running 35s with 3.55 gears good for my truck?" ... Hell no! Upgrade those gears. Yes it is expensive but it needs to be done, no matter how you drive your truck.

If you are going to do a gear change, i would recommend going with 4.56 gears. If you go with 4.10s, you probably wouldnt even feel the difference with 35" tires. Also, as the others said put some lockers or at the least a good limited slip in there. I just recently went from 3.73s and 35" tires to 4.56 and 35" tires, wow what a difference. I would recommend it to everyone.





2004 F150 SC 4x4
4.56 gears all locked up
Air Raid
Troyer SCT2
Flowmaster
315/70/17 BFG AT

I have a Detroit TrueTrac in my rear differential after the stock one crapped out.

Is that good?