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37-inch spare tire solution for running around town and easy trails?

DMoney

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My two discussion points are: 1. Limping home or off a local (easy) trail with a smaller spare tire? and 2. If I run 37's, should I limp home on the 33 or spend the extra $250 for a 35 inch? Same goes for guys wanting 38's or 40's. Do they run around town without a spare or use the a 33 or 35 in a bind.
It will cause your differential to constantly be working and your electronic systems will go nuts.
I see no way that it could damage it much AS LONG AS your lockers are off and it is a short period of time. I would get the 35 it would have a lower effect on the car. A lot of the guys running around in big tires in wranglers tend to get a heavier duty and taller mount, like a swing gate bumper.
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DMoney

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with that spare out from underneath it s a perfect spot for a long range tank for those long outback trips
Good Idea! It should be an option to delete the spare and replace with a bigger tank! But I do see some saftey issues with it. It could be the Ford pinto all over again.
 
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jeepguy225

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It could be the Ford pinto all over again.
hahaha, but CJ.,YT and TJ all came with a gas tank in front of the rear bumper and didn't have pinto problems.
 
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jeepguy225

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It will cause your differential to constantly be working and your electronic systems will go nuts.
I see no way that it could damage it much AS LONG AS your lockers are off and it is a short period of time. I would get the 35 it would have a lower effect on the car. A lot of the guys running around in big tires in wranglers tend to get a heavier duty and taller mount, like a swing gate bumper.
That's why I said to put it on the FAD side and then disable the FAD by disconnecting the plug from it (it takes a screw driver and a few seconds of your time). Then you could use 4-Low with the locker as the smaller spare would never have power to the wheel. Full time 3 wheel drive! But, there could be an issue with brake actuated traction control (I think this can be disabled??). This would be just to get you thru a muddy patch, then go back to rear wheel drive.

Example #1: Doing a home depot run to pick up a new washer and dryer. I cant take the 37 in the bed but I could use the spare 33 just to get home.

Example #2: Going to the local gun range. I take the maintained dirt road on the way in, but on the way out I take the longer, more fun unmaintained dirt road/trail for fun. I then get a flat and assuming a plug will not fix it, I put on the smaller spare tire from under the bed, use the 3 wheel drive option to get thru the muddy parts, then go to rear wheel drive to go the rest of the way.
 
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jeepguy225

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Older 4wd vehicles have locking hubs in the front, which locks the wheel to the axle shaft. The axle shafts are always connected to the diff, but with the hubs unlocked they can turn independently, regardless of whether or not you have a locking diff, because the wheels would not be locked to the axles.

New 4wd's (like the JL) have a FAD on the front passenger side. This replaces locking hubs. This allows both wheels to turn independently in 4wd with the axle unlocked. If you disable the FAD, by disconnecting the power cable going to the actuator, then the front passenger side tire will spin freely (like only locking the front left hub on an older 4wd). My thinking is, by putting the smaller spare on the front right, you could still, technically, use 4-Low with the axles locked, but by disconnecting the FAD wire first, the front passenger side wheel will still spin freely, since the FAD actuator was disconnected before putting it into 4wd, so the sleeve that would normally be pushed over to join the outer axle shaft with the inner axle shaft that is connected to the diff on the right side of the vehicle would not be engaged. This would give you a locked 3-wheel drive setup and leave the spare tire to spin freely. The inner part of the right axle shaft would spin, but since the FAD was disabled, it would not affect the outer part of the shaft.

If you just used 4wd (locked and unlocked) without doing the above adjustments, you would end up with driveline/differential issues because of the smaller spare tire.

Remember, this is only to get out of a bind, a quick fix, a sandy or muddy patch on a trail close to home, where bringing your full size spare wasn't even thought of because you took a detour from your normally paved route down a trail for fun on the way home (I have taken fun detours many times in the past on my way home from work and home depot). Has anyone done something similar? With all the videos I have watched on the FAD, I think it would be fine. If you eliminated the FAD during an axle shaft upgrade, then you would not be able to do this. You would have to limp home in only rear wheel drive.

Dam.. I hope someone figures out how to stuff a narrow 37 inch tall tire under the bed, then I can avoid this potential solution or disaster.
 

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DMoney

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That's why I said to put it on the FAD side and then disable the FAD by disconnecting the plug from it (it takes a screw driver and a few seconds of your time). Then you could use 4-Low with the locker as the smaller spare would never have power to the wheel. Full time 3 wheel drive! But, there could be an issue with brake actuated traction control (I think this can be disabled??). This would be just to get you thru a muddy patch, then go back to rear wheel drive.

Example #1: Doing a home depot run to pick up a new washer and dryer. I cant take the 37 in the bed but I could use the spare 33 just to get home.

Example #2: Going to the local gun range. I take the maintained dirt road on the way in, but on the way out I take the longer, more fun unmaintained dirt road/trail for fun. I then get a flat and assuming a plug will not fix it, I put on the smaller spare tire from under the bed, use the 3 wheel drive option to get thru the muddy parts, then go to rear wheel drive to go the rest of the way.
Don't forget you will need to turn off Electronic stability control.
Your differential will also get hot so don't run it like that long, getting the 35 will reduce the risk of it over heating, will get less hot.
Yeah, that would be fine for getting back on the road. But if you get a flat on the road I wouldn't go through all that trouble of unscrewing things, just keep your differential open it should be fine. If you get a JT with LSD that would be and issue, if I'm right it's only LSD in the rear so if you got a flat on the rear you would need to put a tire from the front on the rear then put the spare on the front. Also some wranglers are full time 4wd, If some gladiators are like this then there is no rwd after getting back on the road- that doesn't matter, you will be fine either way as long as the differential is open.
 

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Dam.. I hope someone figures out how to stuff a narrow 37 inch tall tire under the bed, then I can avoid this potential solution or disaster.
Why not pack a tall skinny? Kind of a weenie tire but real tall, lighter, against a side?
 

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My two discussion points are: 1. Limping home or off a local (easy) trail with a smaller spare tire? and 2. If I run 37's, should I limp home on the 33 or spend the extra $250 for a 35 inch? Same goes for guys wanting 38's or 40's. Do they run around town without a spare or use the a 33 or 35 in a bind.
This. Thats my plan is to carry a 35" under the bed and then use it to limp home in the same way you would use a donut on your average car. I just dont want the spare taking up room in the bed and plan on using a rolling hard tonneau cover and don't like tailgate carriers on trucks as they look awkward to me.
 

Vegas_Sirk

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Older 4wd vehicles have locking hubs in the front, which locks the wheel to the axle shaft. The axle shafts are always connected to the diff, but with the hubs unlocked they can turn independently, regardless of whether or not you have a locking diff, because the wheels would not be locked to the axles.

New 4wd's (like the JL) have a FAD on the front passenger side. This replaces locking hubs. This allows both wheels to turn independently in 4wd with the axle unlocked. If you disable the FAD, by disconnecting the power cable going to the actuator, then the front passenger side tire will spin freely (like only locking the front left hub on an older 4wd). My thinking is, by putting the smaller spare on the front right, you could still, technically, use 4-Low with the axles locked, but by disconnecting the FAD wire first, the front passenger side wheel will still spin freely, since the FAD actuator was disconnected before putting it into 4wd, so the sleeve that would normally be pushed over to join the outer axle shaft with the inner axle shaft that is connected to the diff on the right side of the vehicle would not be engaged. This would give you a locked 3-wheel drive setup and leave the spare tire to spin freely. The inner part of the right axle shaft would spin, but since the FAD was disabled, it would not affect the outer part of the shaft.

If you just used 4wd (locked and unlocked) without doing the above adjustments, you would end up with driveline/differential issues because of the smaller spare tire.

Remember, this is only to get out of a bind, a quick fix, a sandy or muddy patch on a trail close to home, where bringing your full size spare wasn't even thought of because you took a detour from your normally paved route down a trail for fun on the way home (I have taken fun detours many times in the past on my way home from work and home depot). Has anyone done something similar? With all the videos I have watched on the FAD, I think it would be fine. If you eliminated the FAD during an axle shaft upgrade, then you would not be able to do this. You would have to limp home in only rear wheel drive.

Dam.. I hope someone figures out how to stuff a narrow 37 inch tall tire under the bed, then I can avoid this potential solution or disaster.
Im not sure you have to worry about that. I didn't think the Full Time AWD is on anything but SelectTrac models. On my JKU Rubi its RWD all the time unless I put it in 4WD. 95% of the time I don't even need 4WD with the bigger tires (currently I run 35s), and if I got a flat could most likely even on trail run 2WD back home. The only issue is the traction control but thats easy to disable for a short span to limp home or the nearest tire dealer.
 

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I'm not entirely convinced that a 37 won't fit in there. That's a 35 in the picture, and there's still a little room to spare. With the tire aired down, and perhaps a ratchet strap around the circumference or a clamp of some kind to squish the limiting dimension, it could maybe be made to fit.
 

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I'm not entirely convinced that a 37 won't fit in there. That's a 35 in the picture, and there's still a little room to spare. With the tire aired down, and perhaps a ratchet strap around the circumference or a clamp of some kind to squish the limiting dimension, it could maybe be made to fit.
Squishing a tire unevenly is horrible for it. Would have flat spots for sure, I guess if it is just a spare it would still get you home.
 

fixbroke

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Squishing a tire unevenly is horrible for it. Would have flat spots for sure, I guess if it is just a spare it would still get you home.
My hope is that it wouldn't require any more squish than you'd get while parked on a slightly aired-down tire. Working that into a 5-tire rotation could prevent it from becoming a permanent flat spot.
 

homerun

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My hope is that it wouldn't require any more squish than you'd get while parked on a slightly aired-down tire. Working that into a 5-tire rotation could prevent it from becoming a permanent flat spot.
I like the optimism, 37 with the spare underneath would be sweet.
 

TXJT

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Just thinking out loud here...figuratively...

One option that hasn't been discussed is to go ahead and carry the 35" spare and when/if needed, air down the 37's to approximately the same height as the 35 at full street pressure. While obviously not optimal with 3 flat tires and 1 at full pressure, all of the tires would be close enough to the same height to avoid any differential / electronics issues until you can get home or to a tire store.

I have also looked at the picture that fixbroke posted several times and thought there has got to be a way to get a 37" spare up there with a little modification (its only 1" difference on the radius and most 37's are not actually 37" anyways). The exhaust doesn't look to be the constraint but rather the distance between the trackbar and the hitch. Additionally, the "shield" around the spare flares out at the bottom and removal may just be the ticket to getting a 37 to fit...

As far as dragging it all over everything, it couldn't be much (if any) worse than a 35 on a comparable wheel...
 

chrcal14

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Just thinking out loud here...figuratively...

One option that hasn't been discussed is to go ahead and carry the 35" spare and when/if needed, air down the 37's to approximately the same height as the 35 at full street pressure. While obviously not optimal with 3 flat tires and 1 at full pressure, all of the tires would be close enough to the same height to avoid any differential / electronics issues until you can get home or to a tire store.

I have also looked at the picture that fixbroke posted several times and thought there has got to be a way to get a 37" spare up there with a little modification (its only 1" difference on the radius and most 37's are not actually 37" anyways). The exhaust doesn't look to be the constraint but rather the distance between the trackbar and the hitch. Additionally, the "shield" around the spare flares out at the bottom and removal may just be the ticket to getting a 37 to fit...

As far as dragging it all over everything, it couldn't be much (if any) worse than a 35 on a comparable wheel...

I agree on dragging, same width if doing 37 12.5, just bigger around so won't stick down any further.

BFG KM3s are 34.5 for 35s, 36.5 for 37s, so it is a full extra inch each way... but like you said, there is some space already there, seems hard to believe a half inch or so can't be found in there somewhere. Shield probably has to go i'd think, and maybe that will be enough with some fiddling.

Just don't know what's around or behind it.
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