smaller diameter spare tire

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Nov 1, 2021 | 07:05 PM

Gary E

Thread Starter

Laughing Gas

Joined: Feb 2004

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From: sacramento

smaller diameter spare tire

Is this a problem on the rear e locker axle?
I have my stock spare say 32 inches tall or so and I run metric 34.5 inch tire. I think this is bad for a limited slip axle right?
I had to run it on the front and it disables abs and traction control and gave me lots of errors that all went away when I put the right size tire back on.

Nov 1, 2021 | 07:18 PM

BillyE

Fleet Mechanic

Joined: Feb 2018

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Yes it’s bad for LSD. You don’t have an LSD.

Nov 1, 2021 | 07:31 PM

Mlarv

Senior User

Joined: Jan 2021

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Yes it is bad to run it long distance on any corner of the truck. The RPM are more then the rest and the computer is shutting off ABS etc to make sure you know. Run it to get someplace to get the full size one repaired or replaced. Sort of like the doughnut tires.

Nov 1, 2021 | 07:59 PM

SARDiverDan

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Joined: Oct 2011

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From: SoCal/Wyoming

Embrace the pain and get yourself the right size spare. Ford told me that while they do supply a spare, it may not properly fit the vehicle that you have. The same wheel/tire for the 20" set me back over 700 bucks. While they would not give a 20" spare, they said I could take it to a Ford dealership and they would swap out all of my 20" for 18" but I would not receive a credit.

Nov 1, 2021 | 08:10 PM

Ltngdrvr

Lead Driver

Joined: Nov 2005

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You're only supposed to run the spare long enough to get a proper replacement tire installed, just don't use the truck hard on the spare.
If you do that then you're fine, just like on cars that have those tiny donut spare tires.

Nov 1, 2021 | 08:16 PM

chadstickpoindexter

Lead Driver

Joined: May 2021

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From: Uh oh, CA

Another reason I wanted 18’s… my spares the exact same as the 4 on the ground… except the wheels a steelie instead of the sparkle rim.

Nov 1, 2021 | 08:34 PM

JimC_CO

5th Wheeling

Joined: Jul 2021

Posts: 32

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From: Colorado Springs, CO

Quote:

Originally Posted by Ltngdrvr

With a space saver spare, that's definitely true. My 2022 F-350 XLT with the optional 275/70R18 tires came with a matching spare but on a steel wheel. I think I could run that at normal speed even fully loaded. That said, I'd be careful to get someplace to get a replacement tire as soon as I could.

I have driven a truck with a smaller spare on the back with one at 33" and one at 30" but not very far or fast. That truck had a LSD rear but I had to get it off the trail and home.

Jim

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Nov 2, 2021 | 05:53 AM

Joe T

Hotshot

Joined: Mar 2017

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From: Chaz

They make some metric size 18 inch wheel tires close to 34.5 that you can put on your spare wheel. Or you can find a used 20 and put a 285/65 on it that would be the same height.

Nov 2, 2021 | 06:26 AM

#10

Pugga

Fleet Mechanic

Joined: May 2018

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Quote:

Originally Posted by Ding126

The factory 20's have 275/65R20 tires which are just a hair over 34" tall. The spare you have is just a hair over 33" tall (obviously different tires may vary a bit). It's close, but will still be short. I'm pretty sure my spare is a 275/65R18, so just over 32" tall and I'm running the factory 20" wheel and tire setup. If I have to use the spare, I'll just take it slow.

Nov 2, 2021 | 06:51 AM

#11

RidgwaySD

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Joined: Jul 2021

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From: Ridgway, CO

All good advice above... You CAN run the shorter spare on the rear end with the e-locker (unlocked) but I agree, only for as little time as possible. The differential will adapt to the different wheel speeds but this is wearing on the spider gears. The best place to run the smaller spare (in 2wd) is in front because when not in 4wd the front wheels are not connected to the front differential. Other than the ABS sensors freaking out, the front is the best place to run the small spare especially if it is going to be a few days for a replacement tire, which is the current reality. I keep my eye out for a same size spare. I am not so concerned that I am spending $350-400 to get a new one put under the truck but as time passes I should be able to find a decent used one in my size. Then I will run a same size spare, which is ideal, especially for guys travelling cross country towing campers etc.