Upgrade to 31x10.5, What changed?

[storlied]

What exactly changed before you (if you did) fixed the speedometer?

How bad were the shifts on your automatic? (I've read upgrading to 31's screwed up the shift points)
I've got 3.73 Gear Ratio, is it true they're just as good as 3.55 with 31's? or is that BS?
How noticable (or not) was the acceleration difference from your stock tire size?
If you had any rubbing, where was it? Did it cause any damage?

What else am I missing? Is there anything I should know? Anything I need to get done after the upgrade? (besides the obvious speedometer issue)

 

[MountaineerGreen]

You'll be fine with the 31's- do it to it. Speedo will be a little off, not worth the effort, IMO.

 

[storlied]

I've read on this forum that someone was having some serious shift issues before they had the speedo fixed, they said it sounded like the tranny was going to explode.. (ok, maybe i exagerated a little bit..) but still, they said it sounded like it was under some stress, and that the power loss they experienced due to larger tires was cured with the fix?..

and do you know anything bout my gear ratio question?

also, where the hell is that airmax review!!?? =D

 

[Boomer12]

I've run 31's with the stock 3.73 gears for 3 yrs, and 32's for 2 yrs now...
No major problems, alittle slower off the line but the intake and exhaust does help.

 

[smtcapecod]

missing

What exactly changed before you (if you did) fixed the speedometer?

How bad were the shifts on your automatic? (I've read upgrading to 31's screwed up the shift points)
I've got 3.73 Gear Ratio, is it true they're just as good as 3.55 with 31's? or is that BS?
How noticable (or not) was the acceleration difference from your stock tire size?
If you had any rubbing, where was it? Did it cause any damage?

What else am I missing? Is there anything I should know? Anything I need to get done after the upgrade? (besides the obvious speedometer issue)

Fuel economy will be worse. Without upgraded sway bars it'll be subject to more shoving from sidewinds. Brakes won't be as effective. Not saying these changes will be dramatic, but there will be some.

 

[PRS]

Go for it, I'm running 31's with 3.73's and the truck runs great. No adverse shift issues or any problems at all.

 

[brianjwilson]

You'll be just fine. Been running 31's on my 97 Explorer (4.0L 3.73s) for over 3 years with no problems. Acceleration is slightly worse. No noticeable increase in sway or body roll, actually it is better with the 31" LTs than the 235 P tires. Brakes just fine. No tire rub. Speedo is hardly changed and not worth fixing. Still within a couple mph of the radar signs. Go for it, you'll be glad you did.

 

[Donner]

Mine are okay now...

The lift w/coilsprings resolved my rubbing issues... w/o that, they'd still rub. The shifting issue was corrected by a third party.

(tht bumper was for Justdoit... sorry) but the bumpers with 4 light are there too...fabtech

im out...goodnite!

 

[TequilaSnrs087]

Don't worry about it.

I have 3.27s...yes, 3.27s. I went from stock P235/75R15s (29") to 31x10.50s without any real issues. The front bumper is all mangled from multiple wrecks and had to be pulled back to its stock location to prevent rubbing, but other than that there were not fitment issues. Acceleration is slower, but it isn't bad at all. The transmission is doing fine. Shifting isn't really off as far as I can tell. I took the truck out with a handheld GPS unit and the speedometer and odometer were spot on. The truck must have been reading slightly off stock, because it was almost perfect with the 31s on. I have had them on the truck for maybe 3-4K miles now.

 

[Charlie]

I think (I may be crazy here) that the speedometer is calibrated for 30" tires, so before it was slightly under and is now slightly over. My 31's going on as we speak!

 

[MountaineerGreen]

31's with a V8 and 3.73's is cake. I ran 265 75 16's, almost 32's for a long time with 3.73's with no issues. Just lock out OD 35-50, no problems.

 

[Charlie]

Well, you want to know what changed:

I just had mine put on today, and I am very happy with them. There was no rubbing whatsoever. When driving, the steering wheel is easier to turn. Also, the ride is much smoother, because of the extra 'padding' from the larger tire. It seems to not brake quite as well, but I cannot be sure how much of that is the tires, and how much of that is the slightly icy roads. When I drive, the speedometer would have read around 38 with the old tires, but now it is reading around 35. I have not yet figured out if it is more accurate now, or how far off it is of TRUE SPEED. I think it is closer. GPS testing will occur sometime.

Either way, 31's are worth it. When getting in, you can feel that the truck is sitting a little bit higher. Shifting has also been perfect.

Good luck with your 31's

 

[TequilaSnrs087]

Yeah, the ride changed a lot on mine too. It looks beastly with the tires and general beat to hell appearance, but it rides like a Lincoln now on the highway, lol. I keep mine aired up to around 35 psi too.

 

[storlied]

31's with a V8 and 3.73's is cake. I ran 265 75 16's, almost 32's for a long time with 3.73's with no issues. Just lock out OD 35-50, no problems.

What did you mean by lock out the OD 35-50?

And I guess I'm not going to worry about anything with the 31's seeing as how you guys are doin great with them.

 

[MountaineerGreen]

The button on the end of your gear shift, push it, and an orange light comes on that says OD off or something like that. It stops your transmission from going into overdrive, which it will sometimes want to do with oversized tires. You can fell your engine "lugging" to pull, just push the button.

 

[Nocturnall]

Doesn't that also turn on engine braking when you take OD off?

 

[storlied]

I know what OD is, and no.. I'm pretty sure it doesn't give engine braking.. unless you're in 1st or 2nd. So what you're saying is, if it turns off, just turn it back on?.. or what... What causes this? Is it a malfunction or what? It shouldn't turn off randomly... I can understand it turning on though... idk.. please explain..

 

[MountaineerGreen]

The 4R70W is a 4 speed transmission. 3rd gear is 1:1, so every revolution of the engine drives the driveshaft one revolution. 4th gear is overdrive, meaning every revolution of the engine turns the driveshaft faster than the engine is turning, so .73:1 or so. The transmission wants to slip into OD on mine at lower than highway speeds, "lugging" the engine on gentle acceleration. Pushing the OD Off button only lets the transmission operate in gears 1-3. There can be more engine braking because the TC locks in 3rd as well as 4th. Larger tires seemed to make this condition worse on mine, so when driving from speeds 35-50, when I feel the transmission shift into OD, I push the OD off button, bringing the engine back into its useable RPM range. Once at 50+ MPH, I push it again to allow the transmission to shift into OD for highway economy. I also use the OD off button when coming up to a stop, it can slow the truck considerably without using brakes, which saves brakes and gas.

 

[storlied]

Oh yea?? But wait.. is that with the 31's?.. I thought you were running 32+??

What about with OD Off, why does the engine run at a higher RPM in any of the gears?.. Or did I just totally miss something you said..

I need to find an article about the explorer OD system or something... idk..

 

[storlied]

bump