Spare Tire One Inch Smaller

[J0E]

No issue if you put it on the front right and stay out of 4wd. With the fad on that side, from a mechanical stand point it won't matter one bit as it's only connected to the outer axle shaft and won't even turn the spider gears.

Or left side

Just best on the front either side

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[Zandcwhite]

Just save up till you can afford one more tire. The difference of 1" isn't the problem, it is the revolutions per mile that tire will need to achieve to keep up with the other three. This increased revolution will create excessive heat. There are also the numerous electronics that will have to compensate (ABS, etc) for the fact that one tire is moving considerably fast than all three other tires.

For instance the 255 tire is rotating 629 times per mile, where as the 275 is covering the same distance with 609 rotations.

If you needed it in an emergency pinch where you weren't going to go a considerable distance or speed, you're probably fine. But if you need it for a long haul, I wound't personally do it.

Tell that to every donut spare provided with 90% of vehicles these days. It's not an issue at all period. The only reason the donut spare recommends not exceeding 55mph or 100 miles is the garbage quality tire used. Your diffs don't care.

 

[Dyolfknip74]

Most donut spares are smaller than normals. You're fine.

 

[J0E]

Tell that to every donut spare provided with 90% of vehicles these days. It's not an issue at all period. The only reason the donut spare recommends not exceeding 55mph or 100 miles is the garbage quality tire used. Your diffs don't care.

30% have no spare
90% of vehicles these days that have a spare, have a donut
I,m sure you're right but I put my 31 on the front when I below a 37

 

[Zandcwhite]

30% have no spare
90% of vehicles these days that have a spare, have a donut
I,m sure you're right but I put my 31 on the front when I below a 37

Definitely an extra level of safety by using the FAD to effectively disconnect the mismatch. Even my 89 xj came with a donut spare, and it was full time 4wd. Limited slips or locking the diffs will cause problems, but otherwise you are good to go.

 

[roaniecowpony]

Definitely an extra level of safety by using the FAD to effectively disconnect the mismatch. Even my 89 xj came with a donut spare, and it was full time 4wd. Limited slips or locking the diffs will cause problems, but otherwise you are good to go.

Agree. Detroit lockers, Torrington types, etc, it would be better to either put the undersized tire on a uncoupled front axle for hwy use, or limit speed and distance on the axle with those types of diffs. Off-road, it wouldn't matter even using air or E lockers, since tire slippage will accommodate the difference.

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