tire rotation and alignment question

[The motor guy]

My alignment was off and it sort of wore my front passenger tire down more than the front driver. Both front tires were toed in but the front passenger was alot worse. I had an alignment done and rotated the front tires straight to the back. My question is will it harm anything to have one tire slightly smaller than the other since it is worn more? Will it mess up the rear differential any or is it designed to allow both rear tires to spin at different speeds without any harm being done to the rear diff? I didn't know so I increased the pressure in the worn tire to make it slightly larger to make up for the increased wear on that tire. But now I figured I would ask I pretty sure it's ok for the rear diff to spin at slightly different speeds but I want to hear from you guys. If that's the case I'll go drop the psi in that one tire that has more wear.

 

[tinmanSC]

The 50% rule generally applies to AWD vehicles. If the tires are 50% worn, don't replace just one tire, you replace them all (yes, this isn't always true. I know, i know). I assume this would be the general rule for LSD applications as well?

 

[The motor guy]

Well the tires are still good. Just that one is more worn than the others. I think I have just a tad more than 1/4" tread depth on the tires.

 

[The motor guy]

You mean if the tires are 50 percent worn and you need to replace a tire that you should replace all four because the new tire will be larger than the 50 percent worn tires?

 

[willix]

The tire pressure should be calibrated so at operating temps the air pressure increases for the flatest contact patch on the pavement.

Having inside edge wear on one rear tire won't change the pressure requirement. Monitor the tire more.

If things are square with the alignment you should get some use out of them. They are worn uneven & will now wear out prematurely.

The differental doesn't know that the tires are worn.

 

[The motor guy]

Well I didn't mean to complicate my question but let me simplify it. Is it okay for the tires on a limited slip differential to spin at different speeds? I don't think that one tire is worn that much more than the other one. maybe 3/16" smaller.

 

[willix]

The differential doesn't know or care.

 

[The motor guy]

Alrighty then. Thanks.

 

[tinmanSC]

Originally Posted By: motor_oil_madman
Well I didn't mean to complicate my question but let me simplify it. Is it okay for the tires on a limited slip differential to spin at different speeds? I don't think that one tire is worn that much more than the other one. maybe 3/16" smaller.


That's not very much, and you should be just fine. The issue is that if the tires are spinning and different rates, all that energy has to be dissipated, I cannot be used to make the truck go forward. It will end up as heat in the diff, and that's bad. But 3/16 isn't big enough to cause an issue. It's not going to generate heat or cause an LSD to lock.

 

[The motor guy]

So does it still provide power to both wheels or the one that is turning the slowest?

 

[tinmanSC]

Originally Posted By: motor_oil_madman
So does it still provide power to both wheels or the one that is turning the slowest?


Both. The LSD will give power to both, if one starts rotating faster than the other (all the power is going to that one), it will take other measures and more strickly control it's distribution of torque. But this is calibrated (some are even user-adjustable) to ignore common issues. Like when you are taking a turn, say, to the right. The right wheel will have a decreased spin during that turn, because it's on the inside of the turn. It won't engage for something like that, and it won't have trouble dealing with something as small as 3/16 of an inch change in diameter.

Edit: I guess that would be 3/16 change in radius. 6/16ths (3/8ths)change in diameter. Either way, it's not a problem.

 

[danster]

wait a minute here. Did you do anything to correct the alignment? Do you have worn suspension parts causing this wear?

I think that's your priority.

 

[tinmanSC]

Originally Posted By: danster
wait a minute here. Did you do anything to correct the alignment? Do you have worn suspension parts causing this wear?

I think that's your priority.

Originally Posted By: motor_oil_madman
I had an alignment done and rotated the front tires straight to the back.

 

[jorton]

Originally Posted By: danster
wait a minute here. Did you do anything to correct the alignment? Do you have worn suspension parts causing this wear?

I think that's your priority.


Can worn suspension parts cause separated belts?

 

[gathermewool]

tirerack.com/tires/tiretech/techpage.jsp?techid=18

 

[willix]

Tread depth is measureed in 32nds.

The tire still has an overall diameter larger the worn edge.

3/16ths = 6/32nds

 

[JOD]

Originally Posted By: gathermewool
tirerack.com/tires/tiretech/techpage.jsp?techid=18


Here's my answer to that in another thread, where this same question came up on an AWD vehicle: https://bobistheoilguy.com/forums/threads/true-or-false.140180/

You don't air up your driver's side tire a little more when you aren't carrying a passenger, do you??

If a difference of 1/4" is enough to negatively impact something on your car, you need to get a new car.