what do i need to do to fit 31's on a 2wd comanche?

[Wakerider933]

i have an 89 comanche 4.0l a friend is selling me wheels and tires cheap but I'm not sure what i would need to do to make them fit. can i just add spacers in the front and a helper leaf in the back? how much lift would i need? the tires are 31x10.5x15 and the wheels have a 4 inch backspacing. i want to keep it reasonable low. i just want it driveable a little rub is ok. I'm not going off roading.

[Geonovast]

5 speed or automatic? If you're running with 3.07 gears that thing's gonna dog pretty good.

 

I believe you can stuff 31s with a 2 inch lift.

[Pete M]

What wheels are they? Stock Jeep rims or other brand/aftermarket?

[Wakerider933]

its a 5 speed, and its no dog i chirpped the tires going into third the other day cause i accidentally pulled out in front of some dumbass with no lights on at 8 pm i rarely need to use first gear unless I'm pulling a trailer or starting on a steep hill.

[Wakerider933]

cragar d windows

[Pete M]

Adding 31 inch tall tires will MAKE it a dog. It's the same as installing a crappier gear ratio in the axle. Being 2wd though, it's pretty easy to grab a new axle from the junkyard to get a gear ratio that will better match the new tire diameter. :thumbsup:

 

Those are aftermarket rims and likely have ~3.5" to 4" of backspacing which will put the tires into the flares when turning (and I'm not talking about "only at max turn", I'm talking about at about half-turn). 3" of lift (4" for 2wd MJs) is generally required to accommodate aftermarket rims with 31" tires. Jeep rims will work better and with less lift. I have 0 lift on my 90 (which will be about 1" of lift for a 2wd MJ) and only added WJ lower control arms to prevent rubbing at full lock.

 

 

[Wakerider933]

I'm not at all worried about the gear ratio. I'm not racing anyone. its my daily driver. i can get the wheels and tires for 275 the tires are almost new. i was gonna add a leaf in the back and put spacers up front and gain 2 inches all around.

[Pete M]

I had problems with occasionally stalling in intersections and I only had only 30 inch tires on my 2wd/4.0L. :ack: I'm not kidding.

Also, 2" of lift for you is only 1" of lift on a 4wd MJ and is likely not enough to run 31s on aftermarket rims without tearing into the bottom corners of the fenders.

Don't forget that you'll need an alignment after lifting an MJ any amount.

And I'm not exactly impressed with that price. What kind of tires are they?

 

I personally wouldn't do what you're contemplating.

[Geonovast]

It's not about racing. Dogging the motor = worse mileage. That and you're going to throw your speedometer off. Also gearing starting off in a higher ratio is harder on the axle, and if you have a D35 you could easily break it.

[Pete M]

It's a pretty simple task to swap in a 3.55 geared XJ axle.

[mjeff87]

I have a real nice MJ D35, 4.56 ratio for sale at the moment in the classifieds......we can get 35's on it for you with that :brows: :brows:

 

Jeff

[Eagle]

You can run 31x10.50s on factory rims with NO lift.

 

If you have a 5-speed and 3.07 gears you won't be happy with them, and the reason has nothing to do with clearance. It'll just drive like someone hooked a 1,000 pound anchor to the rear bumper when you weren't watching ...

[Wakerider933]

once again I'm not worried about the gearing i can change the axle out if i want in a couple hours i have done it already and if i switch to lower gears my mileage will be equally bad as if it was bogged down which i think you guys are over emphasizing. I'm not off roading or going for zero to 60 times. i had 30's on it it wasnt bad i don't think 31's will be that much different. and my speedo is driven 5 mph over anyways so it will be way closer.

[Geonovast]

If the the motor spinning faster always equaled out to worse mileage, then 3.07 would probably be the only gearing option, if even that low. Just because the motor is spinning faster it does not mean it's using more fuel. If it's dogging and spinning too slow, it will cause you to use more fuel.

 

Again, none of us are telling you that you should regear so you can win races. I went from 205/75R15s to 235/75R15s on my 4.0 with 3.07, and definitly noticed a power difference.

[Pete M]

The best fuel economy will generally come when the engine is in its sweet spot of maximum torque. Adding the bigger tires drops it out of that zone. Adding 3.55 or 3.73 gears in the back will bring it back up. 4.10s will likely be too much for 31s. My mileage dropped as I went from 215s to 30s, then came back up when I installed 3.55s (after the 3.07 Dana 35 blew up on me when turning a corner).

[Eagle]

Actually, Pete, I disagree with you. I think 4.10 is the optimum ratio for 31s. I say that having run 31x10.50s with 3.73 gears. The overall final drive ration (as measured in terms of MPH per 1000 RPM) is exactly the same as a stock vehicle with an automatic, 3.55 gears, and 225/75R15 tires. It's quite driveable on the street that way, but not a good crawl ratio for any even semi-serious wheeling. Overall, 4.10s are a better choice. The 3.73s make a good ratio with 30s -- which is how I happened to have them.

 

The 3.73s went into the MJ instead of the XJ simply because the MJ was virtually undriveable with 31s and 3.07 gears. I grew up driving manual transmissions, I prefer manual transmissions -- and I couldn't drive the thing. I would have destroyed the clutch within a month. To put that in perspective, the original clutch on the '88 XJ was replaced at 204,000 miles, because the slave cylinder quit. The clutch disc could have gone another 100,000 miles based on the (lack of) visible wear.

[Pete M]

Ya know, if I ever get the 88 up and running again, I've got 4.10s in the axles and the storage tires are little ol' 31s. I'll drive it around like that for a while and see what happens. I'll report back with my findings. :thumbsup: Of course that's if I get it drivable again. :shake:

[BLHTAZ]

In order to properly fit the 31's on your truck , mounted on the Cragar wheels, a 3" lift would be the correct thing to do. I have 3.5" lift and 31" Swampers on mine and the fit is just right. They don't rub anywhere (but it's close), and it looks good.

 

Mine is a driver only with 3.07 gears, and while it is a little slow, it still does well at 16-17 mpg around town. 3.73 gears are in it's future somewhere though...

[MrSimon]

I have the same wheels and 31s on my truck (4WD). Here is a pic of what the 31s looked like with stock 4WD suspension. I couldn't even drive around the block without some major rubbing.

 

Here is the same set up with exactly 3" of lift. No rubbing with normal driving, but some rubbing offroad.

 

I have an auto and 3.55 gearing and the truck is a dog. Sure, it will get up to speed .... you just have to be patient ;)

 

Since you have a stick, you MIGHT be ok with 3.07s and 31s. It really does come down to preference. And, you'll never know how it really drives until you try it.

 

Regarding lift. If you really want to run 31s, I'd recommend a 3" lift .... and do it properly the first time or your ride will suck and you'll get all kinds of vibrations. Spend some time reading this site - tons and tons of lift ideas for all different price ranges.

 

PS - where do you live? I need a set of 2WD leaf springs, and I've got a nice new set of 3" lift leaf packs that would be perfect for you. Maybe we could work something out. PM me.

[Wakerider933]

all I'm worried about is making them fit ill deal with the gearing if i decide i want to change it. I'm asking if they will fit with a 2 inch lift. i measured alot and it seems like they should

 

i live near toledo ohio i might be interested

 

thanks BLHTAZ and MrSimon your input was very helpful

[Pete M]

No they won't. You have to remember that a 2wd MJ sits 1" lower than a 4wd. So when they say that you'll need 3" of lift, that's 3" to a 4wd MJ and that'd be 4" higher than you currently sit. It all has to do with the backspacing of the rims you'll have. Stock Jeep rims will work, Cragers will not.

[BLHTAZ]

With a 2" lift, you will likely get them "on", but fit...no. The term "fit" means that when installed, they do not rub on anything at full lock-to-lock steering or at full articulation of the suspension. If they touch anywhere, then they do not "fit".

 

This is the best side shot I have of mine with the 3.5" lift & 31's, but it has changed a little since this picture.

 

[MrSimon]

You sound like you really want to do this, so I say go for it man. For very little money you can get some used 2" spacers for the front and get an AAL for the rear ... or even get a junk yard pack and make your own AAL.

 

Throw on the new tires and drive it. If you are happy with the ride, great!!

 

If you run into any of the issues listed here, you aren't out that much money ..... and we'd all be happy to help you try something different.

 

I think we can all understand that a there is a certain amount of trial and error that goes into modifying old trucks.

 

all I'm worried about is making them fit ill deal with the gearing if i decide i want to change it. I'm asking if they will fit with a 2 inch lift. i measured alot and it seems like they should

 

i live near toledo ohio i might be interested

 

thanks BLHTAZ and MrSimon your input was very helpful

[possum]

Yes they will fit. I had zero problems with rubbing with stock suspension until I wheeled it with 31's at stock height. But just driving around town they should be fine. My truck is 2wd.

[BLHTAZ]

Yes they will fit. I had zero problems with rubbing with stock suspension until I wheeled it with 31's at stock height. But just driving around town they should be fine. My truck is 2wd.

Please don't tell him that when everyone else in this thread has already told him corectly that those wheels & tires will not work on a stock 2WD truck. MAYBE if they were on stock wheels, but not the set-up that is being asked about...there will be serious rubbing issues. My 31's on aftermarket wheels and 3.5" lift come close to rubbing, so there is NO WAY that they would work on a stock 2WD.