prov1ml

I plan to keep the wheels stock..

frdvschvy

3.31's are not ideal but you will be fine. It will just be a little lazier than a truck with 3.55 gears.

prov1ml

Maybe this will give me a reason to go with the 275/65/20 instead of the 285/65/20 I originally planned on

Halfshell1

It will really come down to the owner. Some will be fine with 3.31s and a tire pushing 35". Others will be disappointed. I know I wouldn't be happy with it.

dcarr

i have a '13 5.0 with 3.31 and the 275/65/20 firestone destination mt's. it still takes right off and i still pull my 7800lb camper fine. it was quicker with the smaller tires but still fast enough with the bigger ones. dont forget to adjust your speedo for the larger tires. i did this with a tuner and got the extra power that way for it.

prov1ml

So, any opinions on if I would be helping myself out by going with the smaller 275/65R20s instead of the 285/65R20s? Would there be a difference or would any difference be negligible?

stage2

If the gearing isn't sufficient, you can always change the ring and pinion gears like I'm going to do. Just make sure you have a Ford tech do it and use motorcraft parts so the warranty won't be voided.

prov1ml

That was going to be my next question -- If it would make sense to change them out.

Any idea what that will run? (ballpark)

Kenn213

I was told that swapping gears on the 2015 is more involved than previous years by someone knowledgeable on the subject (head of mod shop). I don't know much about it though, so can't offer much more.

stage2

You'll need both front and rear if it's 4wd, about $420 or half that for rwd. Plus labor.