Dumb Spare Tire Question

[jerrygcoffey]

I just ordered 4 T/A KO2s that were on sale (see this thread). I'm currently running Patagonia MTs. Both Tires are 315/70R17. Will I be able to use my spare MT with 3 ATs in a pinch? What about on the highway? Risks?

Thanks for any info! Thinking I should've bought 5 ?‍

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[azwjowner]

The Jeep will be fine from a mechanical standpoint. But the mismatched spare will eat at you every time you look at the rear of the Jeep until one day you replace it.

 

[Jeep Wick]

As long as the size is the same, you will be fine. Just be aware in slippery conditions that handling may be inconsistent.

 

[jerrygcoffey]

As long as the size is the same, you will be fine. Just be aware in slippery conditions that handling may be inconsistent.

I believe there might be about an inch difference in true diameter. Thanks for the info y'all

 

[C.Sco]

It's a lot better than the donut spare that comes with most vehicles

 

[jerrygcoffey]

It's a lot better than the donut spare that comes with most vehicles

This reply made me realize how unnecessary this thread was. Thanks! ?‍

 

[stumblinhorse]

This reply made me realize how unnecessary this thread was. Thanks! ?‍

Not quite so fast. If you run a mis-match spare on any Jeep vehicle with a 4H auto setting for the t-case, you will destroy the transfer case in few hundred miles. So the people are speaking generalizations, you do that on a 392, you will destroy the t-case, you do that on a 4xe you will destroy the t-case. It depends on what transfer case/option you have on your Jeep.

 

[jerrygcoffey]

Not quite so fast. If you run a mis-match spare on any Jeep vehicle with a 4H auto setting for the t-case, you will destroy the transfer case in few hundred miles. So the people are speaking generalizations, you do that on a 392, you will destroy the t-case, you do that on a 4xe you will destroy the t-case. It depends on what transfer case/option you have on your Jeep.

Can you elaborate on this? I have a 2018 JL 2.0T if that helps.

 

[C.Sco]

Can you elaborate on this? I have a 2018 JL 2.0T if that helps.

He's referring to models which do not have a 2-Hi mode on the transfer case shift knob. Not sure if yours does or not, but I think it does. My 4xe Rubicon does, but I think the 4xe Sahara does not. None of the 392's have a 2-hi mode. I think most, or maybe all, of the 2.0T's have it.

If you're running a spare that has a slightly different diameter than the other 3 tires, it will put a lot of stress on your transfer case if you drive in anything other than 2-Hi, so that's why he mentions that it's important to not do that if you don't have a Jeep with a 2-hi mode, and if you do have a 2-hi mode then make sure to leave it in that mode until you replace the spare with a tire of a matching diameter to the other 3.

 

[Jeep Wick]

One inch difference in diameter, I don't know. I wouldn't use 4 wheel drive with it. If you have 4 auto on the shifter, the spare will need to be the same size.

 

[jerrygcoffey]

He's referring to models which do not have a 2-Hi mode on the transfer case shift knob. Not sure if yours does or not, but I think it does. My 4xe Rubicon does, but I think the 4xe Sahara does not. None of the 392's have a 2-hi mode. I think most, or maybe all, of the 2.0T's have it.

If you're running a spare that has a slightly different diameter than the other 3 tires, it will put a lot of stress on your transfer case if you drive in anything other than 2-Hi, so that's why he mentions that it's important to not do that if you don't have a Jeep with a 2-hi mode, and if you do have a 2-hi mode then make sure to leave it in that mode until you replace the spare with a tire of a matching diameter to the other 3.

Okay I understand now, I think. To drive in 4 wheel drive Hi and Lo gear the tires need to be the same diameter. (Wondering if I should start paying more attention to getting the tires even when airing down...)

I drive on road in rear-wheel drive. I wasn't aware some Jeeps didn't have a rear-wheel drive option. But this is great information, it sounds like if I need to use that spare on the trail I would want to limp it in rear-wheel drive off the trail.

 

[jerrygcoffey]

Based on the spec sheets I found, KO2 has 34.4" diameter and Patagonia has 34.7" Seems to be very minimal difference. Add to that the fact the tread is worn way down (don't know if that's included in the calculation), and it's probably about the same.

 

[C.Sco]

(Wondering if I should start paying more attention to getting the tires even when airing down...)

Don't stress about it when you're off-road, it's only a potential problem on dry pavement.

When you're offroad, the dirt/sand/whatever will just make your tires slip if one of them is spinning a little faster or slower than the others, so your transfer case will never really get stressed that hard. Dry pavement is where it's a problem because tires can't slip.

 

[jerrygcoffey]

Don't stress about it when you're off-road, it's only a potential problem on dry pavement.

When you're offroad, the dirt/sand/whatever will just make your tires slip if one of them is spinning a little faster or slower than the others, so your transfer case will never really get stressed that hard. Dry pavement is where it's a problem because tires can't slip.

Okay makes sense. I didn't know they're making Jeeps that only have 4WD, interesting.

 

[Flip]

I just ordered 4 T/A KO2s that were on sale (see this thread). I'm currently running Patagonia MTs. Both Tires are 315/70R17. Will I be able to use my spare MT with 3 ATs in a pinch? What about on the highway? Risks?

Thanks for any info! Thinking I should've bought 5 ?‍

Hey Jerry, how did you like the Patagonia MT tires? Did they do a good job off-road, how many miles did you get out of them?

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