Mismatched spare vs. 4 corners.

2867 Views 8 Replies 6 Participants Last post by Gotlime?, Aug 5, 2013

rick325

Discussion Starter · Aug 1, 2013

I have a new-to-me JKU sport that is rocking the stock 16 steelies on 29s. Needless to say, I am going up in tire size (to 33s).

My plan is to go with a 285/70R17 (11.4" wide) Duratracs. Can I get away with just changing the wheels and tires on the 4 operating hubs, and then put a cover to hide the 29" spare? I'd want to do this for a couple of reasons:

1. Don't want to change out bumper and/or extend 3rd light if I can avoid it. Mostly $ concern.
2. I save money. I can buy one less 17" rim and one less Duratrac, saving me about $400.
3. Easier to use for the kids/wife. The tailgate will just be lighter with the stock 29" on there.
4. Less overbearing look--wife and I are debating the rock-crawler look vs. a more "friendly" mall crawler. I got her to the 33 Duratrac's, but think the jeep may look "simpler" without one hanging on the back too.

However, I am concerned about a few things:
1. Will the spare even work, having a 29" spare when the other 3 sides are 33". It would be a true true spare. Note that our offroading (for now) is going to be simple trails with the kids, I don't anticipate getting stuck by myself anytime soon.
2. Will it look odd to have a (covered) smaller spare on the back?
3. What if I wanted the real spare at some point. Maybe go and buy 5 wheels and stash the 5th just in case?

Thoughts??

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gold knight

· #2 · Aug 1, 2013 (Edited)

You can do it yes but we still know what's hiding under there

1) The tire will fit no problem. I have 285/70R75 and it is a snug fit (tire rests on the bumper) but if you go aftermarket wheels you would need extended rubber bumpers on the tailgate.
2) Yep it will cost less.
3) Not that much difference really.
4) That's subjective... bigger tires with a smaller spare has always looked goofy to me.

1) No. Maybe in an emergency but not even sure about that (especially if you have limited slip rear) If you have a flat you will have to get it fixed immediately.
2) Yes
3) If you aren't doing it now, might as well wait and buy one later.

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rick325

Discussion Starter · #3 · Aug 1, 2013

gold knight said:
You can do it yes but we still know what's hiding under there

1) The tire will fit no problem. I have 285/70R75 and it is a snug fit (tire rests on the bumper) but if you go aftermarket wheels you would need extended rubber bumpers on the tailgate.
2) Yep it will cost less.
3) Not that much difference really.
4) That's subjective... bigger tires with a smaller spare has always looked goofy to me.

1) No. Maybe in an emergency but not even sure about that (especially if you have limited slip rear) If you have a flat you will have to get it fixed immediately.
2) Yes
3) If you aren't doing it now, might as well wait and buy one later.

Thanks.

1a) Glad to know it fits (snugly)---is that for the bumper and the 3rd light (so no extension required)? Good point on the bumpers.
4a and 2b) Goofy--good word.
1b) This is the real question. Not sure what happens when on wheel is a good 2" shorter than the rest with a limited slip...

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gold knight

· #4 · Aug 1, 2013

rick325 said:
Thanks.

1a) Glad to know it fits (snugly)---is that for the bumper and the 3rd light (so no extension required)? Good point on the bumpers.
4a and 2b) Goofy--good word.
1b) This is the real question. Not sure what happens when on wheel is a good 2" shorter than the rest with a limited slip...

1a) The 285/70R17 you are looking at would probably fit without even touching the bumper. Here's a pic if the 285/75

the old tires 265/70R17 for comparison

so yours would be somewhere in between.

1b) not positive but if it does have lsd I'm sure it wouldn't be good for it. The wheel sensor would also be reading the difference and the ESP might interpret it as wheel spin.

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rick325

Discussion Starter · #5 · Aug 1, 2013

gold knight said:
1a) The 285/70R17 you are looking at would probably fit without even touching the bumper. Here's a pic if the 285/75

the old tires 265/70R17 for comparison

so yours would be somewhere in between.

1b) not positive but if it does have lsd I'm sure it wouldn't be good for it. The wheel sensor would also be reading the difference and the ESP might interpret it as wheel spin.

Thanks for the pics. re: wheel spin---isn't that what 4wd is for

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Cavallini03

· #6 · Aug 2, 2013

I could be wrong.. but if you do have LSD in the rear and thats where the flat is, wouldn't it make more sense to take a front tire and put it in the back then put the smaller spare up front? That way you can keep it in 2wd and just be a little lobsided in the front but still drive-able?

If you plan on keeping these tires for a while, I'd say get the matching spare just for peace of mind. Plus I think it looks pretty goofy with the small spare.
You can pick up some 17" take off's from a rubicon or sport S for fairly cheap if you watch forums/craigslist.

Just my 2 cents.

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b1pig

· #7 · Aug 5, 2013

i bought a new set of tires from a local shop and asked if he had any used of the same size laying around. i got a free used BFG A/T mounted on my spare. its a spare and it doesnt go in the rotation. i have a rubicon, so if i'm gonna use it offroad with the lockers, having a matching size spare is a must. i dont hide my spare. doesnt matter to me. what matters most is that it holds air, has "some" tread on it and will go on wherever i need it. would be a pain in my back to change two tires because one is flat.

with an open diff, you can run a slightly smaller tire for a short time. you just have to be cautious of the handling and speed.

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awl4928

· #8 · Aug 5, 2013 (Edited)

Your abs will get very angry about the miss matched tire size and its likely you will have to pull the fuse under the hood I believe its J18 in the event you put that spare on.

Personal experience of mismatched Jk tire size. Similarly don't put it on the same axle you have an auto locker installed in.

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Gotlime?

· #9 · Aug 5, 2013

I have a 37" KM2 spare and I'm running 37" MTR/Ks and I'm worried about that size difference. New MTR/K vs worn KM2..................

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