4.0 tire size question

[sarasota]

i have a 99 XLT 4x4 i bought about 3 weeks ago and i already am lookin to get higher haha. but my question is.. how does the 4.0 do with larger tires. im not looking at anything ridiculous just maybe 33's.. a couple people around here think that i wouldn't have enough power but i don't see that it would decrease too much.

thanks, jake

 

[97BlackBetty]

The power is there, you just need to regear to stay as close as possible to stock. Either 4.10's or 4.56's should be good for you. Im assuming that you already have 3.73's. The 3.73's will do an alright job but you will definately see a difference. Personally I would shoot for the 4.56's. Cause you know that eventually you will be putting 35's on. Of course then you would want at least 4.88's. Oh hell, any way you go your screwed. Welcome to the land of indecision.

All I can say is do your research and accept that you have the bug.

 

[krugford]

You might notice a little bit less grunt off the line. What the stock tire size on that? 245/75/16? What's the current axle ratio? If you tell us what you've got now, you can calculate what gear ratio would bring it back to stock and it'll give you an idea of what you'll lose.

 

[sarasota]

yes, that is the stock tire size and i BELIEVE it is 3.73.

how much would 31's change the power? because if this is gonna be some big mess with regearing then i should just save my money until i can buy a decent suspension setup and throw somethin serious under there

 

[pillen140]

dont do 31's, they look almost the same as stock. my 3.0L has 33's on it, with 3.73's and i hardly notice(that much anyway). i little power loss, but not much. i went with 33x10.5r15, to save about 15lbs of weight for each tire. i did 3" blift, and 2inch leveling kit on mine. the 4.0 has way more hp and torque, so you should be okay.

 

[dogboy]

I went from stock 28's (235/75/15) to 33x12.5x15's and I noticed the differance, but it isn't that bad really. It's ALITTLE slower off the line, but over all, the thing I notice most is that the rpm's are about 1800 in OD at 60mph as opposed to before where it was about 2200rpm at 60mph.
I am sure the auto tranny plays a BIG part in not noticing the change as much, compared to if I had a manual. I might re-gear this summer though, depends on how things work out.

My milage went from about 15.5mpg down to about 14.5mpg. Not a huge diffeance. And yes, I used how far I actually went, not just pluging in what the odometer said like some people (odometer read short).

EDIT: I also only have about a 2" suspension lift, and they fit fine. Had to "modify" the bumper slightly, and the rear of the front wheel opens slightly. Looking at the truck, most poeple would not know I did anything. But probably could have gotten by without the fender/ bumper changes if it was going to stay on the street.

On wheels, get the right backspacing!!! Wrong backspacing can make on tire fit, or the same tire not fit.
I have 15x8 with 3.75 backspacing for my wheels and I think that is perfect.

 

[86ford]

your fine. get whatever you can afford. just beware of buying bias ply tires if you plan on doing much road driving. they are loud, wear fast, tend to shake the steering wheel and sometimes the truck. buy what ya can. re-gearing is a luxury and often times a PITA. its expensive, so unless you are making a drastic tire change dont do it (drasitic is 30s to 35s or 37s). my STOCK 200k 2.9 b2 with 355s pushes 31inch TSL bias ply tires on steel rims, now granted it dosent like it but it will do it. your 4liter has TWICE the power of my 2.9 so dont worry to much, heck i had a 4liter ranger with 33s and 308 gears (it was a 92 and the motor is much weaker than yours). IF you do wheeling other than mud bogs you will want to re-gear, other than that your fine.

86