Circumference compatibility between 31x10.5R15 and 265/75R15 on same axle

[TJMexico]

I am currently running 31x10.50r15 on my machine. I will likely be buying new tires soon. If I do, I may have to to go a metric sized tire, which would be a 265/75R15. However, one of the current tires (31x10.50r15) is still in very good shape (was mounted as a spare and not rotated in by the P.O.), so I´d like to keep that as my spare.

My concern is whether the difference in circumference between the two different measurements is enough to cause problems with the differential if I drive it for a substantial distance. The difference in 31x10.5r15 is less than one inch, but over a couple of thousand revolutions that can add up.

Does anyone have any experience with this or any inside knowledge about it?

 

[voodooridr]

Tiresize.com is a fantastic tool

I would think it would cause issues eventually

 

[machoheadgames]

Should be fine. Look at actual tire specs of the tires you’re looking at. For example, Toyo makes the 31x10.5 and 265/75R15. From Toyo, the 31x10.5 is 676 revs/mile while the 265 is 677 revs/mile. That is such a close match that you would never know the difference.

That said, tire choice is really poor in 265/75, so I would rather go with the 31’s if possible.

 

[JKP]

If you have a LS rear, I wouldn't run the mismatch on it for any distance.

Just swap the tires around to put the mismatch on the front.

 

[jjvw]

If you have a LS rear, I wouldn't run the mismatch on it for any distance.

Just swap the tires around to put the mismatch on the front.

I would expect the LSD to notice more every time it experiences a turn or whenever a tire is low on air pressure.

 

[JKP]

There's no way to know what the actual difference in diameter is without knowing the brands and models of the tires.

However, most 31x10.50s R15s are not 31" in dia. Most are only around 30.5".

 

[06GEEP]

I would expect the LSD to notice more every time it experiences a turn or whenever a tire is low on air pressure.

Or if one tire is wore down more than the other...
I wouldn't worry about it If it were me. So many variables we could come up with, but every time I hear this debate I think that if the gears can't handle SOME difference in wheel speeds from side to side, then every rearend should have gears that are welded together so the wheels can't go different speeds.

 

[jjvw]

There's no way to know what the actual difference in diameter is without knowing the brands and models of the tires.

However, most 31x10.50s R15s are not 31" in dia. Most are only around 30.5".

If he is concerned about it after he buys the tire, he can adjust tire pressures to even out the rolling radius when measured from the ground up to the center of the axle tube.

 

[jjvw]

Or if one tire is wore down more than the other...
I wouldn't worry about it If it were me. So many variables we could come up with, but every time I hear this debate I think that if the gears can't handle SOME difference in wheel speeds from side to side, then every rearend should have gears that are welded together so the wheels can't go different speeds.

When we are already beginning with what appears to be less than a 1/4" difference in tire radius, the entire concern feels silly.

 

[JKP]

Or if one tire is wore down more than the other...
I wouldn't worry about it If it were me. So many variables we could come up with, but every time I hear this debate I think that if the gears can't handle SOME difference in wheel speeds from side to side, then every rearend should have gears that are welded together so the wheels can't go different speeds.

It's not the gears. It's the clutches in a LSD if so equipped.

 

[06GEEP]

When we are already beginning with what appears to be less than a 1/4" difference in tire radius, the entire concern feels silly.

Yeah, kinda, sorta.

 

[jjvw]

It's not the gears. It's the clutches in a LSD if so equipped.

Do you truly believe that the countless number of people out there driving vehicles with clutched LSDs are overwelmingly running identically sized and uniformly inflated tires? Or are most of them doing good enough to not experience any meaningful amount of problems that would make this a valid concern?