Thoughts on a smaller spare tire?

pcpopcorn

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Incorrect diameter tires turn at different speeds. For a Rubi that is staying in 2wd to get from the side of the road to a tire shop, it could work. Not ideal by any means and I specify a Rubi because it doesn’t have a limited slip but is open until the locker is engaged. For someone that has a limited slip if you had a flat on the rear, you could put a front matching tire on the rear and the spare on the front. This creates a significant amount of additional work but would work.

Easiest is to have matching tires.

Brett
I did just this saved $2K
I have a 2 door Rubicon and went with Mopar Bead Locks (Not Mounted as Bead Locks) and 35" Cooper ST Pros
I put a tire cover on my 33" Spare and figure I saved $2000.00 by not buying the wheel, tire and Tailgate Reinforcement.I read on other forms guys doing this as well.
I'll limp to the tire store





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caged

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you guys know how metric tire sizes work, right?
sure, a 255 tire is narrower than a 295 tire, but that middle number, if both are 70, well, that's 70 percent of the width is the sidewall height, so even tho it's narrower, it will be a much smaller diameter tire when you do the math.

255 is width in millimeters, the 70 is the percentage of width, that's your sidewall height. then you have to multiply that number by 2, since you will have two sidewalls to add up, then the 17 is the rim diameter. so 255 divided by 25.4 (millimeters to inches) is 10.3 inches wide. times that by .70 for sidewall height is 7.02. double that number since there is two sidewalls in the equation, is 14, then add the rim size of 17 makes that a 31 inch tire.

now if you do the math on a 295/70/17, you will find that it works out to a 33 inch tire.
run those different size tires front/back and put the jeep in 4lo, add lockers and you will grenade your t-case/drive shafts or even diffs.
 

rustyshakelford

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you guys know how metric tire sizes work, right?
sure, a 255 tire is narrower than a 295 tire, but that middle number, if both are 70, well, that's 70 percent of the width is the sidewall height, so even tho it's narrower, it will be a much smaller diameter tire when you do the math.

255 is width in millimeters, the 70 is the percentage of width, that's your sidewall height. then you have to multiply that number by 2, since you will have two sidewalls to add up, then the 17 is the rim diameter. so 255 divided by 25.4 (millimeters to inches) is 10.3 inches wide. times that by .70 for sidewall height is 7.02. double that number since there is two sidewalls in the equation, is 14, then add the rim size of 17 makes that a 31 inch tire.

now if you do the math on a 295/70/17, you will find that it works out to a 33 inch tire.
run those different size tires front/back and put the jeep in 4lo, add lockers and you will grenade your t-case/drive shafts or even diffs.
For once standard is easier than metric....that sounds super unamerican so USA, USA!

Brett
 

blnewt

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you guys know how metric tire sizes work, right?
sure, a 255 tire is narrower than a 295 tire, but that middle number, if both are 70, well, that's 70 percent of the width is the sidewall height, so even tho it's narrower, it will be a much smaller diameter tire when you do the math.

255 is width in millimeters, the 70 is the percentage of width, that's your sidewall height. then you have to multiply that number by 2, since you will have two sidewalls to add up, then the 17 is the rim diameter. so 255 divided by 25.4 (millimeters to inches) is 10.3 inches wide. times that by .70 for sidewall height is 7.02. double that number since there is two sidewalls in the equation, is 14, then add the rim size of 17 makes that a 31 inch tire.

now if you do the math on a 295/70/17, you will find that it works out to a 33 inch tire.
run those different size tires front/back and put the jeep in 4lo, add lockers and you will grenade your t-case/drive shafts or even diffs.
I fully understand all the tire math, my spare is just a "limp to the shop" or a matched spare for our long trips. And I'm aware of the dire consequences running 4Lo w/ diameter variance. Good info for those that aren't aware.
 

Arterius2

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I fully understand all the tire math, my spare is just a "limp to the shop" or a matched spare for our long trips. And I'm aware of the dire consequences running 4Lo w/ diameter variance. Good info for those that aren't aware.
might as well just remove the spare altogether...
 

blnewt

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might as well just remove the spare altogether...
Why? For our long trips that are often many miles from any shops I will have all matching tires (and this is about 4x a year). I could remove it when I run my larger setup but that's just more work and w/ the tire cover it looks ok.

If I did run a larger tire setup all the time I for sure would have that larger tire back there FWIW.
 

Firefly

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Thx for this post. I was contemplating doing the same for the same concerns as what you stated. Yes, I know it could lookabut odd but I thought that if it saves me from installing a relocation AND reinforcement brackets to the tune of several hundred dollars then I'd risk it. Mine are 35s so I'd need the brackets. But, after reading the replies, I'll stay with installing a matching spare as well. Now, on to researching the best reinforcement options.
 

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