Different spare tire diameter, auto locker (1 Viewer)

[DKW]

hello all

My spare has is a different manufacturer and slightly worn, so is around 1.5" less in diameter than my new tires. I will also soon have an auto locker fitted. there are a number of reasons I do not want to bore you with on why I don't get a new spare, but that would be a last resort right now.

I searched on here and I am still not clear on how to run temporarily if I use my spare, especially with auto locker. Which shaft to remove, put spare on rear, etc.

If anyone can get their head around this and offer advice (apart from buying a larger spare) I would be grateful.

Cheers

 

[thatcabledude]

If you’re real worried you could always put spare on the front, and move the front tire to the back so the two rear tires are the same.

 

[-Spike-]

hello all

My spare has is a different manufacturer and slightly worn, so is around 1.5" less in diameter than my new tires. I will also soon have an auto locker fitted. there are a number of reasons I do not want to bore you with on why I don't get a new spare, but that would be a last resort right now.

I searched on here and I am still not clear on how to run temporarily if I use my spare, especially with auto locker. Which shaft to remove, put spare on rear, etc.

If anyone can get their head around this and offer advice (apart from buying a larger spare) I would be grateful.

Cheers

It would be helpful to know which axle the locker is going into, and whether or not you still have the viscous coupler in the transfer case. If you do, the tire size matters, and you shouldn't run it regardless of which axle the locker is on. Unless you do plan on pulling a driveshaft.

 

[DKW]

Auto locker on rear and I could pull a shaft.viscous coupling still working

 

[DKW]

So a solution could be to put spare on front, remove front drive shaft and lock center diff?

 

[Grandlooser]

At some point one of us needs to ask why you would go to great lengths to run a wrong tire, rather than just having a correct one? It's just a spare tire so getting a near junk one for free is fine.

 

[DKW]

If this is unclear, this is for the spare. I have 4 new geolanders. Spare is a used KO2, both are 33". Used tire has a smaller diameter and its the spare. I am asking this question in case I get a puncture and need to temporarily use the undersize spare. Struggling to get new tire size in spare location due to PO custom exhaust, yes the 1.5" difference makes all the difference in the spare tire space.

 

[Grandlooser]

No we know.

You could always plan on under inflating your other 3 to compensate in the event?

 

[-Spike-]

No we know.

You could always plan on under inflating your other 3 to compensate in the event?

I don't think it works that way. The full circumference of the tire still needs to travel over the ground. It might help a little, as much as the fully inflated tire might stretch, but that ain't much.

 

[BILT4ME]

I don't think it works that way. The full circumference of the tire still needs to travel over the ground. It might help a little, as much as the fully inflated tire might stretch, but that ain't much.

Yes, under-inflating works the same as changing the "rolling radius" of the tire. An underinflated tire will have more rotations per mile than a properly inflated tire.

 

[DKW]

Thanks for the replies. I have to decide whether removing front drive shaft and halting any wheeling activity I am doing is more\less desirable than making space for new size tire. Saying that I have only had 2 flats in 30+ years.

 

[flintknapper]

Thanks for the replies. I have to decide whether removing front drive shaft and halting any wheeling activity I am doing is more\less desirable than making space for new size tire. Saying that I have only had 2 flats in 30+ years.

Unless you tear a sidewall.....just fix the flat. Carry a GOOD plug kit and a source of air. Only use the spare if you have a catastrophic failure/injury to your primary tire. Auto Locker should be of no concern.....it will just 'ratchet' more under certain conditions, won't hurt it. Your VC however might be a concern if there is a gross disparity in tire sizes and you have to travel a long distance.

 

[jonheld]

No we know.

You could always plan on under inflating your other 3 to compensate in the event?

Tires are not balloons. Altering tire pressure does NOT change the rolling length of the tread. It just flattens out at the bottom.

 

[Grandlooser]

It changes the distance between the hub center and the ground. Let all the air out of a tire and tell me it doesn't spin faster than the other tire at the same ground speed.

 

[jonheld]

Yes, under-inflating works the same as changing the "rolling radius" of the tire. An underinflated tire will have more rotations per mile than a properly inflated tire.

I'm going to have to argue with this statement.
Again, tires are not balloons. Altering tire pressure does not change rolling length of the tread, unless you deflate to the point where the sidewall is now in contact with the road.
The steel belts in the tread do not change length due to inflation, they allow the tread to flex, but the rolling length remains constant.

 

[Eyedaho]

Yes, under-inflating works the same as changing the "rolling radius" of the tire. An underinflated tire will have more rotations per mile than a properly inflated tire.

Tires are not balloons. Altering tire pressure does NOT change the rolling length of the tread. It just flattens out at the bottom.

 

[Grandlooser]

I'm just going to go ahead and apologize to OP now for his thread.

 

[-Spike-]

Yes, under-inflating works the same as changing the "rolling radius" of the tire. An underinflated tire will have more rotations per mile than a properly inflated tire.

It changes the distance between the hub center and the ground. Let all the air out of a tire and tell me it doesn't spin faster than the other tire at the same ground speed.

Okay. It does not. The entire tread surface contacts the ground. The only way to make it shorter is to fold it.

 

[Grandlooser]

True. However tire DO fold and distort when under inflated no?

 

[hoser]

I'm going to have to argue with this statement.
Again, tires are not balloons. Altering tire pressure does not change rolling length of the tread, unless you deflate to the point where the sidewall is now in contact with the road.
The steel belts in the tread do not change length due to inflation, they allow the tread to flex, but the rolling length remains constant.

Altering the pressure does change the tire's radius. The tire's tread will squirm and wear quicker to accommodate. Take a look at the early style, 1st generation, indirect tire pressure monitors. They measured a difference of tire rotation via ABS sensors. There was no tire pressure sensor. The under inflated tire will have a slightly smaller diameter (and present as more rotations to the ABS/wheel sensor).