Are my tires supposed to rotate on the rim? - 986 Forum - The Community for Porsche Boxster & Cayman Owners

speedyspaghetti · 09-23-2018, 07:07 PM

Hey everyone -

So I've been chasing down this vibration issue, and something I noticed when taking my car to get the rims checked for any dents was that my center caps which I had recently aligned perfectly were now misaligned. So, to double check I used a piece of chalk and marked a straight line on each tire down to the center of the wheel. Much to my surprise, both wheels on my passenger side had rotated almost 360 degrees over the course of a 20 minute drive.

Is this normal? Could this be causing my vibration issue at highway speeds and overly jerky steering on poor roads?

maytag · 09-23-2018, 07:23 PM

So, you think your tires are spinning on the rim, as opposed to your center caps spinning in the wheel?

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thstone · 09-23-2018, 07:50 PM

It is completely normal for a tire to rotate on the rim (to some degree). With that being said, 360 deg in 20 mins seems somewhat excessive.

And yes, this could easily cause an out of balance situation. The wheel and tire are balanced with the tire at a certain location. If the tire was to creep around the rim, then the weight might not be in the correct location in relation to the tire causing an out of balance condition.

A better way to check this is to mark the tire at the location of the valve stem and then check later to see if the mark on the tire has moved in relation to the valve stem.

speedyspaghetti · 09-23-2018, 08:11 PM

Quote:

Originally Posted by maytag

So, you think your tires are spinning on the rim, as opposed to your center caps spinning in the wheel?

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I'm pretty certain, but I'll try again tomorrow by marking the valve stem.

speedyspaghetti · 09-23-2018, 08:12 PM

Quote:

Originally Posted by thstone

It is completely normal for a tire to rotate on the rim (to some degree). With that being said, 360 deg in 20 mins seems somewhat excessive.

And yes, this could easily cause an out of balance situation. The wheel and tire are balanced with the tire at a certain location. If the tire was to creep around the rim, then the weight might not be in the correct location in relation to the tire causing an out of balance condition.

A better way to check this is to mark the tire at the location of the valve stem and then check later to see if the mark on the tire has moved in relation to the valve stem.

Good idea - I'll retest again tomorrow and see if it is still just as bad. What could be causing this? An issue with how the tire was mounted? Or maybe a defect with the rim?

maytag · 09-23-2018, 08:13 PM

While I won't argue with stone, I would clarify that, while it may happen, it's not supposed to.
In my experience, a tire slipping on a rim is caused by under inflation, combined with aggressive driving.

If a tire has rotated on a wheel, it is no longer balanced.

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speedyspaghetti · 09-23-2018, 08:21 PM

Quote:

Originally Posted by maytag

While I won't argue with stone, I would clarify that, while it may happen, it's not supposed to.
In my experience, a tire slipping on a rim is caused by under inflation, combined with aggressive driving.

If a tire has rotated on a wheel, it is no longer balanced.

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Tire are at 29 psi in the front and 36 in the rear, cold. My drive today was not aggressive - just from Home Depot back to home, kept her under 4k rpm the whole time.

ndfrigi · 09-23-2018, 11:01 PM

wow! tire should not slip or move around the wheels/rim. Like other mentioned if too low tire pressure and aggressive driving will make that happen. But with 29psi and just driving on local street, tire should not slip from the rim.

Quadcammer · 09-24-2018, 05:36 AM

With a clean rough bead and proper mounting a tire should not move on the rim under normal driving. Drag race cars have this issue on hard launches but thats with 500+ hp and sticky rubber

maytag · 09-24-2018, 05:44 AM

Quote:

Originally Posted by Quadcammer

With a clean rough bead and proper mounting a tire should not move on the rim under normal driving. Drag race cars have this issue on hard launches but thats with 500+ hp and sticky rubber

Drag race cars with 500hp don't have this problem any longer, hehe. We used to have this problem, when we were using bias ply tires. But with the advent of drag radials, it takes a lot more than 500hp to spin the tire on the rim.
Offroad / rock crawlers have this problem a ton, because they air down to 8-12psi. That's why they have what's called a "beadlock" on them.... because they don't want tires spinning on the wheel either.

Again: if your tires are slipping on the wheel, this should be corrected.

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Burg Boxster · 09-24-2018, 08:23 AM

Quote:

Originally Posted by thstone

It is completely normal for a tire to rotate on the rim (to some degree). With that being said, 360 deg in 20 mins seems somewhat excessive.

Yep - agree 100%.

Always chuckled when I ran Toyo Proxy R888s and how much they moved around a rim... particularly rear. I'd index when mounting new and see how quickly I could get one to rotate 360 degrees around...

speedyspaghetti · 09-24-2018, 08:52 AM

Quote:

Originally Posted by ndfrigi

wow! tire should not slip or move around the wheels/rim. Like other mentioned if too low tire pressure and aggressive driving will make that happen. But with 29psi and just driving on local street, tire should not slip from the rim.

God, I hope this solves my vibration issue... it has been driving me absolutely insane.

speedyspaghetti · 09-24-2018, 08:53 AM

Quote:

Originally Posted by Burg Boxster

Yep - agree 100%.

Always chuckled when I ran Toyo Proxy R888s and how much they moved around a rim... particularly rear. I'd index when mounting new and see how quickly I could get one to rotate 360 degrees around...

I'm guessing it took you more than 20 minutes?

speedyspaghetti · 09-24-2018, 09:43 AM

Quote:

Originally Posted by maytag

Drag race cars with 500hp don't have this problem any longer, hehe. We used to have this problem, when we were using bias ply tires. But with the advent of drag radials, it takes a lot more than 500hp to spin the tire on the rim.
Offroad / rock crawlers have this problem a ton, because they air down to 8-12psi. That's why they have what's called a "beadlock" on them.... because they don't want tires spinning on the wheel either.

Again: if your tires are slipping on the wheel, this should be corrected.

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While I love the idea of my car having 500+ hp, I'm gonna guess that is not the case... I'll get this looked at. Thanks!

MWS · 09-24-2018, 10:28 AM

Quote:

Originally Posted by speedyspaghetti

God, I hope this solves my vibration issue... it has been driving me absolutely insane.

I believe this was suggested in your other thread, but I would recommend seeing if you can find someone/someplace that would let you briefly borrow a set of replacement wheels (for at least your fronts) to confirm that your vibration issue lies with either your rims or tires.

And for the record, I'd have never guessed that your tires were spinning on the rims. Good catch...

Jim 'n' SC · 09-25-2018, 01:12 PM

I seriously doubt yours tires are rotating on the rim. I've never heard of it and I've been around cars and tires a long time.

particlewave · 09-25-2018, 02:01 PM

Quote:

Originally Posted by Jim 'n' SC

I seriously doubt yours tires are rotating on the rim. I've never heard of it and I've been around cars and tires a long time.

It does happen.
If he chalked them, it's kind of hard to mistake.

speedyspaghetti · 09-25-2018, 02:17 PM

Quote:

Originally Posted by Jim 'n' SC

I seriously doubt yours tires are rotating on the rim. I've never heard of it and I've been around cars and tires a long time.

I found it hard to believe too, but I cannot think of any other reason why the chalk marks would be moving.

Era Vulgaris · 09-25-2018, 02:39 PM

Are you saying you put a continuous line of chalk on both the tire and the wheel, and after driving some distance the chalk line "split" into two lines on the same tire/wheel?

Or are you saying you marked lines on your front and rear tires, and after driving they are no longer aligned in the same direction? This instance, along with center caps, are impossible to keep aligned from front to rear because your front and rear tires are different sizes. And they won't stay aligned passenger side to driver side, because when you make a turn the outside wheels turn more than the inside wheels.

But if it's the first case, where the single line on one tire/wheel splits into two, that's freakin weird man.

speedyspaghetti · 09-26-2018, 07:48 AM

Quote:

Originally Posted by Era Vulgaris

Are you saying you put a continuous line of chalk on both the tire and the wheel, and after driving some distance the chalk line "split" into two lines on the same tire/wheel?

Or are you saying you marked lines on your front and rear tires, and after driving they are no longer aligned in the same direction? This instance, along with center caps, are impossible to keep aligned from front to rear because your front and rear tires are different sizes. And they won't stay aligned passenger side to driver side, because when you make a turn the outside wheels turn more than the inside wheels.

But if it's the first case, where the single line on one tire/wheel splits into two, that's freakin weird man.

You know, I think I need to re-do my test. I had some doubts while I was falling asleep last night and this morning I checked and my center caps are a bit loose on that side compared to the other. I'll re-check tonight and report back.