Question on Spare Tire Size!

[BS67]

Ok folks....have a question. Just had new Toyo AT3s installed. Size is 255/70R17s. Ordered a used tire for a matching spare and when it got here it's a 265/70R17. On tire calculators the 255s are 31.1" and the 265s are 31.6". Will that 1/2" difference be a problem if I had to use it or am I safe if I keep the speeds down? Thanks!

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[Grumpaw]

1/2 inch overall diameter, but only 1/4 inch higher....won't make a bit of difference.

 

[BS67]

1/2 inch overall diameter, but only 1/4 inch higher....won't make a bit of difference.

Thanks Steve! Have an email to UnitedTires over it......will see what they say! Maybe keep the tire and they can refund me the cost

 

[Grumpaw]

Check with them, but, if any of your 4 rolling tires lost 3 or4 lbs of psi it would probably go down 1/4 - 1/2 inch and your pressure sensors most likely wouldn't register it.

 

[BS67]

What I was thinking. Thanks for the input!

 

[Frenchy]

It won't make a huge difference, but I would recommend having it as close as possible. A true matching spare would be best

 

[DukeCanBuildit]

Hey Brian, like others are saying, it’s a small difference and you should be fine.

The regular spare would be out by just as much if it had to be used late in the life of your original tires (they’d be worn down - the spare would be “new”).

I think the biggest concern with spares and higher speeds is the rear diff. With mis-matched diameters, the differential is, well, differentiating. Keeping the speed down helps mitigate the problems associated with this - hence the max. speed warning sticker on the spare.

If you had to use it on a front flat, it wouldn’t really matter as long as you were not using 4WD. The axle spins independently and it doesn’t mess with the front diff when in 2H.

If you had a rear flat and you were too worried about it affecting your rear differential, you just need to rotate a front to where the flat is and put the spare on the front. Twice the work but peace of mind.

 

[BS67]

Hey Brian, like others are saying, it’s a small difference and you should be fine.

The regular spare would be out by just as much if it had to be used late in the life of your original tires (they’d be worn down - the spare would be “new”).

I think the biggest concern with spares and higher speeds is the rear diff. With mis-matched diameters, the differential is, well, differentiating. Keeping the speed down helps mitigate the problems associated with this - hence the max. speed warning sticker on the spare.

If you had to use it on a front flat, it wouldn’t really matter as long as you were not using 4WD. The axle spins independently and it doesn’t mess with the front diff when in 2H.

If you had a rear flat and you were too worried about it affecting your rear differential, you just need to rotate a front to where the flat is and put the spare on the front. Twice the work but peace of mind.

That's what I was thinking front vs rear! Thanks Duke! Appreciate your input! Will see what UnitedTire has to say about replacing!

 

[Langwilliams]

I put 265/70-17's on my ranger an left the spare the stock size. I figured that as long as I didn't use 4wd I could limp it to the tire store. I planned on getting a 265/75/16 to replace the spare before doing any long drives but I ended up trading it in.

 

[BS67]

Got contacted by UnitedTire. They were really apologetic over the wrong size. They offered for me to keep this tire with a $15 reimbursement and I accepted. Figured with the posts above I could still use it a spare. Thanks for the help and insight. Getting the tire mounted and balanced this afternoon!

 

[BS67]

Accepted their offer............the tire ended up costing me $21.

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