Running with an undersized spare

[Dogboyslim]

I just purchased some aftermarket wheels/tires (315/70/17), but they only had 4 so I have to wait a month for the spare. I'm going wheeling this weekend. do I keep the street Sahara wheel that I still have as a spare or just go without?

I'm thinking I'll bring it. Pros are that I can at least limp to a shop to get the larger tire repaired/replaced. The only cons I can think of is the ridicule I will get from the other folks there, and the need not to drive too far too fast to avoid premature differential wear (same as the donuts in a smaller car).

Am I thinking of this correctly, or would you just go without the spare?

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[Andy2434]

I always carry a tire repair kit in my vehicles. In my Jeep, depending on the situation, I also carry a CO2 bottle and/or a Viair 12V compressor.

 

[TJ2018]

The spare could help you limp along if need be. Wouldn't hurt to bring it but I'd follow @Andy2434 s suggestion of a patch kit and air supply.

 

[Tritonman]

Running an offsize spare in relation to whats currently being ran can cause more damage then not having a spare. The size you are running isn't that much of an odd size that i wouldn't be surprised if someone there has a spare that size you can borrow.

Its more about the diameter of the tire than width, if the diameter is off, the smaller tire will have more rotations than the larger one which can cause issues. You now have 2 tires attempting to rotate at 2 different speeds. Even worse of its an LSD.

I cant remember but aren't the stock Sahara wheels/tires 18's?

Edit: Definitely don't do it if you have the Full Time 4wd option.

 

[Dogboyslim]

Problem solved. Discount Tire just called to tell me my spare is in! I can pick it up before I go. Now I just have to figure out how to carry it before my reinforced carrier arrives!

 

[Tritonman]

Problem solved. Discount Tire just called to tell me my spare is in! I can pick it up before I go. Now I just have to figure out how to carry it before my reinforced carrier arrives!

You should be fine to run it where your spare is for a little while until you get your carrier.

 

[melendez69]

@Andy2434

...and air supply.

 

[WranglerMan]

I have been running with 315’s and no beefy spare tire carrier for over a year and have had zero issues

 

[UNC Rubicon]

Problem solved. Discount Tire just called to tell me my spare is in! I can pick it up before I go. Now I just have to figure out how to carry it before my reinforced carrier arrives!

You shouldn’t have any problems as long as you make sure your tire is making contact with your bumpstops.

 

[Dogboyslim]

Well, the rims are now mine!

 

[roaniecowpony]

The difference in diameter would cause overheating of the differential at highway speeds, eventually. I don't know how long that would take.

 

[Arrowhead]

The difference in diameter would cause overheating of the differential at highway speeds, eventually. I don't know how long that would take.

You do realize that with you FAD disconnected, the front differential spider and side gears are spinning amongst themselves faster that the planets around the sun right? Granted, they are not under load but still.

I don't know why people get all freaked out about having a different sized spare. Manufacturer's have doing that for decades. It's perfectly fine for emergencys and short distances to get you out of the woods and to a service station if you can't fix it on the trail. Now I wouldn't go 85 MPH for 1000 miles either as yea, would probably cause some damage - i.e. fry your limited slip (but then again it's probably shot already if you have it).

And yea, if you blow a tire way back in the wilderness and have to go back through gnarly trails with your stock Saraha mall spare after you had upgraded to 40" stickies, than yea getting back out will be more challenging than getting in.

Would I do it? Heck no! I'm not going to be "that guy"

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