Tire size difference.

[SwampDog]

My on-road tires are a different size than the spare:
275/60R20SL (33" x 10.8" x 20") Spare: P265/70R17 (31.6" x 10.4" x 17")
Wondering 1) why? 2) Is not the 1.4" difference in diameter enough to cause differential damage over time/miles and 3) can the spare be changed to the larger tire size, i.e., will it fit in the under-the-vehicle mount?

Thx folks!

 

[swathdiver]

I have read on these forums that you can put a 33" tire in the spare tire well. The current spare should only be used on the front axle and not with 4x4 engaged.

 

[OR VietVet]

If you have a flat on rear and have to mix the size, would be best to be in 2wd and swap a front tire to rear and put the spare on the front.

 

[Alessandrolomb]

As far as I know, using a spare tire that's significantly different in size can potentially cause differential damage over time. So, I think that the 1.4" diameter difference in your case could be enough to cause issues if the spare is used extensively.

 

[RST Dana]

There is some discussion about road hazard replacements on the rear being an issue since you would have one new tire and one used, even though the same tire size. I can’t locate the source, but I remember my service mgr found a source indicating only replacing one drive line tire, even though it was the same size, would be problematic due to tire height from tire wear height on the remaining tire.

 

[Marky Dissod]

There is some discussion about road hazard replacements on the rear being an issue since you would have one new tire and one used, even though the same tire size.
I can’t locate the source, but I remember my service mgr found a source indicating only replacing one drive line tire, even though it was the same size, would be problematic due to tire height from tire wear height on the remaining tire.

Sounds like this advocates an all-five tire rotation schedule.
That'd minimize the wear differences between tires.

 

[RST Dana]

Sounds like this advocates an all-five tire rotation schedule.
That'd minimize the wear differences between tires.

Yes. But even 3/32 difference between old and road hazard replacement could equate to between 1/4 / 1/2 inch in circumference difference. Meaning, new tire rotates 2 less times than used one on the same axel per mile.

 

[Marky Dissod]

Yes.
But even 3/32 difference between old and road hazard replacement could equate to between 0.25" - 0.50" in circumference difference.
Meaning, new tire rotates 2 less times than used one on the same axle per mile.

Sounds like a damn good reason to rotate all 5 tires often enough to annoy most driver/owners.
(Y'all who change your oil less often than once every 5000 miles bewilder me.)

That said, is 0.50" of roll-out discrepancy between two tires is enough to warrant concerns about differential wear?
I'm earnestly asking.

 

[Miami-Dade]

@SwampDog Moved you here from P. Vendor Sales.

 

[RST Dana]

Sounds like a damn good reason to rotate all 5 tires often enough to annoy most driver/owners.
(Y'all who change your oil less often than once every 5000 miles bewilder me.)

That said, is 0.50" of roll-out discrepancy between two tires is enough to warrant concerns about differential wear?
I'm earnestly asking.

I have driven thousands of miles on many vehicles and never thought once about diff wear after having a tire replaced due to road hazard. Maybe I was lucky, but so far, I have never had an issue with stuff in the diff or the flux capacitor needing assistance.