tire moving on rim at the track

[NewArt]

So, I'd heard of this; someone had posted here on the forum. Curious, I marked my track wheels with new tires (RE-71R) before a 2-day event. This is the right rear
wheel after 2 days:

[piper6909]

That's mind-blowing. The question is, was it the acceleration or braking that did it? If that's a pick of the right tire, it would be braking. If it's the left tire, then it would be acceleration.

[NewArt]

Actually. I think it’s the left rear. I get my hands mixed up! ��

[rexcramer]

The original pic doesn't look like all that much of a shift. I remember other posts' showing +/-6" IIRC from track days. I would imagine the rears show far more of a shift than the fronts?

EDIT: Maytag looks about right.

[NewArt]

Originally Posted by rexcramer

The original pic doesn't look like all that much of a shift. I remember other posts' showing +/-6" IIRC from track days. I would imagine the rears show far more of a shift than the fronts?

EDIT: Maytag looks about right.

Yeah, I thought that the previous post was an anomaly, but I now see that this is common for track tires. Maytag’s pictures bowled me over! The movement of my tires is negligible in comparison.

[maytag]

Originally Posted by NewArt

Yeah, I thought that the previous post was an anomaly, but I now see that this is common for track tires. Maytag’s pictures bowled me over! The movement of my tires is negligible in comparison.

The guys at the track that day told me that's very common. I'd have never believed it, had it not happened to me.

And piper, as for what tire is what in my photos, I don't recall now. But I'd think it only makes sense that the rears spin under power (so the wheel turns "forward" in the tire) and the fronts under braking (so the tire turns "forward" on the wheel).

Dunno.

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[piper6909]

Originally Posted by maytag

The guys at the track that day told me that's very common. I'd have never believed it, had it not happened to me.

And piper, as for what tire is what in my photos, I don't recall now. But I'd think it only makes sense that the rears spin under power (so the wheel turns "forward" in the tire) and the fronts under braking (so the tire turns "forward" on the wheel).

Dunno.

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If we know which side the wheels/tires came from and the direction of the rotation, we can determine if it's braking or accelerating causing it. I suspect that even an S doesn't have enough torque to cause this under acceleration.

My theory is that it's caused by breaking, and the front tires rotate more than the rears, because the fronts brake harder.

I probably won't track until next year, and if I do I probably won't drive it as hard as some people on here because I don't have the skills. So it would be great if someone would try the experiment and note which corner each tire/wheel was on. Maytag, would you be so kind?

[piper6909]

Originally Posted by NewArt

Actually. I think it’s the left rear. I get my hands mixed up! ��

Then it must be happening during acceleration. I was expecting the opposite. I didn't think they had enough torque to do that.

But then again, it looks like all 4 tires moved, so it has to be during braking. Are you sure it came from the left (driver's) side?

[maytag]

Here's a recent thread about it. You'll see I wasn't convinced, until I experienced it in dramatic fashion.

https://r.tapatalk.com/shareLink/topic?url=http%3A%2F%2F986Forum%2Ecom%2Fforums%2Fs howthread%2Ephp%3Ft%3D73341&share_tid=73341&share_fid=31135&share_type=t&link_source=app

You can see my marks on the sidewalls, which lined up with the valve stems at the beginning of the day.

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[piper6909]

Originally Posted by maytag

Here's a recent thread about it. You'll see I wasn't convinced, until I experienced it in dramatic fashion.

https://r.tapatalk.com/shareLink/topic?url=http%3A%2F%2F986Forum%2Ecom%2Fforums%2Fs howthread%2Ephp%3Ft%3D73341&share_tid=73341&share_fid=31135&share_type=t&link_source=app

You can see my marks on the sidewalls, which lined up with the valve stems at the beginning of the day.

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I noticed each pair of tires rotated in opposite directions. Is one pair fronts and one pair rears?

[NewArt]

Well, so much for precision wheel balancing!

[maytag]

Originally Posted by NewArt

Well, so much for precision wheel balancing!

Yup. That's exactly what I said in the other thread. Never paying to balance track tires ever again

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[NewArt]

So, do street tires do this in day to day driving? Anyone checked?

[Anker]

Originally Posted by NewArt

So, do street tires do this in day to day driving? Anyone checked?

If you bother to read all the printed material you get when the tires have been replaced you see see that you have to be careful with hard acceleration and brakind for a couple of days to prevent exactly this problem from happening.

[piper6909]

Originally Posted by Anker

If you bother to read all the printed material you get when the tires have been replaced you see see that you have to be careful with hard acceleration and brakind for a couple of days to prevent exactly this problem from happening.

Who bothers to read that!?? haha!

[NewArt]

Originally Posted by Anker

If you bother to read all the printed material you get when the tires have been replaced you see see that you have to be careful with hard acceleration and brakind for a couple of days to prevent exactly this problem from happening.

Haha, well I’m pretty gentle on my street tires but I don’t think that I’ll be avoiding hard acceleration/braking on my track tires!

[kk2002s]

So in off road motorcycling, many tubeless tires and rims use a Rim lock device to lock the bead down to the rim. Off road car/truck racers have to lock the beads down on to the rim so it makes perfect sense that a sports car on a track would do the same thing.

[BYprodriver]

Originally Posted by kk2002s

So in off road motorcycling, many tubeless tires and rims use a Rim lock device to lock the bead down to the rim. Off road car/truck racers have to lock the beads down on to the rim so it makes perfect sense that a sports car on a track would do the same thing.

Most likely because of the low air pressure for off road traction.

[piper6909]

So, judging from the position of the valve stems, unless the rear tires rotated over 270 degrees, the top pic should be the tires from the left, correct?

[Geof3]

How in the world does this happen and not break the bead/seal? Are the tires getting hot enough to somehow soften the bead enough to allow this? That’s pretty crazy. I’ll have to mark mine next time out...