[NickyRacerBoy]

This lately has been an issue.
Rears are moving alot and causing heavy out of balance vibrations.
The fronts too are moving but only slightly.
Apexi rims that are not nurled. Any tricks of the trades to stop this?

[cdb95z28]

I've experienced this also.

My Forgelines do not have any knurling, and since they have a gloss black finish, they are very smooth. I have roughed up the area where the tire sits on the rim. I also clean the tire's bead and the wheel with some BraKleen to remove any manufacturing oils. With these wheels, I have found, that the tire moves, but there hasn't been an issue with imbalance, atleast none that I can feel. It seems that any weights that mine takes is for the wheel more than the tires. More often than not any new mounting puts the weights in similar spots on the wheel. Usually opposite of the TMPS sensor/valve. I've been running the 3R the past couple years, so maybe they are very well balanced on their own.

But, lately my tire guy has been careful with not using excessive tire lube. The lube should only be on the wheel's ramp, not on the bead itself.

We've tried Windex as a lube, as someone here on the forums had that suggested by some Bridgestone guys. We found it very difficult to get the tire to seat though. Just not slippery enough.

With the minimal lube, it does take more pressure to seat the bead, but it seems to be working. They will get almost all of the bead seated, then deflate and add some more lube to the remaining unseated spot then repressurize. This seems to work. Of course, there is a greater risk with higher seating pressures. My tires are not moving as much lately as they have in the past. I'm fortunate to have the owner of the tire shop, along with another employee, who are very open to try anything and are never in a rush to do the job.

A few other things I use to my advantage. I try not to use the newly mounted tires on the track too soon. I will run them on the street to get some heat in them to help dry out the lube. I also wash the wheel/tire immediately after mounting to remove the excess lube that is around the bead, then I let them dry out in the hot sun. Whether this helps or not is debatable, but I have been having better luck with all of these methods. Another factor that may matter is that I am not running low cold pressures anymore in order to help the outer shoulder at the beginning of a session. So maybe with me running higher than GM's recommended cold pressures (26psi) that also helps minimize the slippage.

I think trail braking can be one factor that creates the slippage. And I have found that the tire that moves the most is my RR tire. Similar to your experience. My track is a CW rotation and the RR tire sees the least amount of loading. I believe this lets it rotate more because it doesn't have as much dynamic vertical force acting on it.

When I get a new tire mounted I paint stick a reference line to it and the wheel, that way I can see it moving. I have also moved the tires from side to side, in the hopes that with them spinning in the opposite direction, that they will try to go back towards their original location. This has worked!

Also, do not overlook the build up of rubber marbles on the tire as a source of vibration. I have found that driving on the rough rumble strips that are prevalent on our 4 lane highway shoulders are good at removing the buildup.

Here is GM's info on the slippage:

https://static.nhtsa.gov/odi/tsbs/20...40436-9999.pdf

[cdb95z28]

More info:
https://www.toyotires.com/media/1492...n_complain.pdf

[racerx8]

Nick if they are using any of that "soap lube" when mounting tires you'll likely get that tire/rim issue. I had this issue myself, I now have knurled Apex 19's still got an inch or three movement on two wheels. If they use something like "windex" it will evaporate quickly after mounting and greatly minimize the tire rotation on rim.

[Redlinez]

I remember when they were developing the Z28, they had issues with this and had to modify the wheel with those Trofeos.

[RUQWIKR]

I have never NOT had movement on rims (knurled, not knurled), slicks, Hoosiers, Goodyears, dry lube, soap, bacon grease (whatever that tire grease is made of, LOL).

I ask myself why do I even bother balancing. Matter of fact, every few sets, I don't balance just to see and haven't had issues.

Then, given the amount of track rubber that melts in after sessions, the original new balance goes out the window even if the tires didn't move.

Think about the speeds, crazy thick sidewalls, and braking forces in F1. The tires are not bead locked, so, they have to move a ton on the rim.

[Move_Over]

They all rotate...even with knurling. You should see how much the IMSA tires rotate haha.

[NickyRacerBoy]

All good replies!
When I was at VIR vibration got so bad, jack hammer, that I took rears off and went to speed shop on premises and had rebalanced. Felt great for couple of sessions.

Ive always had slippage and vibration but not tp this extent. I was definitely honing my trail braking at VIR if that has anything to do with it.

Lately I have had a different shop mount my tires.
Ill ask what he uses, pretty sure that white stuff.

[gtfoxy]

Anyone use screws like drag wheels?

I always ran screws below 1.60 60’ capability. While not entirely necessary until faster, it’s cheap insurance. I would certainly understand a reluctance to drill holes in expensive rims, but it is what it is.

[RUQWIKR]

As an ex long time drag racer, most drag wheels have flat vertical flanges for rim screws. Others use bead lock wheels. If it was such an issue, you’d see those in high level road racing cars, which you don’t. The added mass of true bead locks isn’t worth it.

[gtfoxy]

I haven’t really seen it either, was just curious.

[rickybobby]

Originally Posted by NickyRacerBoy

This lately has been an issue.
Rears are moving alot and causing heavy out of balance vibrations.
The fronts too are moving but only slightly.
Apexi rims that are not nurled. Any tricks of the trades to stop this?

My solution is to rotate the tires from left to right every track day. It is not perfect but is somewhat self correcting.