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Tires Spinning on Wheels


phat ralph

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Guys,

 

Yet another tire question! But I marked my tire to valve stems during my last track day at VIR. I am experiencing the tire slipping/spinning on the wheel. Is this normal? If not what needs to be done to prevent it? In the picture below you will see a silver Sharpe line a couple of inches away from the valve stem. This was on the rear of the car but the fronts are similar.

 

se9cg9.jpg

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Hey Ralph! That's pretty normal. I'm the wheel and tire guy for RRT Racing. I see this all the time. Our Grand Am car would routinely spin the front tires 90+ degrees on the rim. If it really gets that bad you could request your tire guy mount your next set of tires "dry", without using any lubricant to mount the tire on the rim. That can be tough if he doesn't have a really good tire machine.

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x2. Pretty normal.

 

If it really gets that bad you could request your tire guy mount your next set of tires "dry", without using any lubricant to mount the tire on the rim. That can be tough if he doesn't have a really good tire machine.

 

When I mount my track tires I only lube "half" of the tire (the inside bead) and leave the top bead dry. That way the tire is still fairly easy to mount.

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You don't balance your race tires!? OK, I am missing something fundamental here.... Can you explain this to me?

 

I can understand that as the tire slips around the wheel, a previously balanced tire will become slightly unbalanced since the tires are probably not perfectly symmetrical (the reason for the balancing weights in the first place, and those weights are attached to the wheel, not the tire).

 

But it still seems to me that you want to at least START with a balanced tire, so that as the tire slips on the wheel, you go from balancing to slightly unbalanced. If you don't balance them at all, aren't you almost guaranteed to have a slight wheel vibration?

 

Just trying to educate myself....

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Rim slip is pretty normal. Has to do with bead ring dia and wheel bead seating dia.

 

Hey Ralph! That's pretty normal. I'm the wheel and tire guy for RRT Racing. I see this all the time. Our Grand Am car would routinely spin the front tires 90+ degrees on the rim. If it really gets that bad you could request your tire guy mount your next set of tires "dry", without using any lubricant to mount the tire on the rim. That can be tough if he doesn't have a really good tire machine.

 

100% against this.

 

Tire lube dries up after 30 mins of installing. It's not what is causing the tire to slip after that. Dry mounting will lead to the bead not seating fulling in the bead well and/or tearing the bead seating area which is a major safety issue.

 

If it does not seat the tire can take a set and it will feel like a flat spotted tire forever. If it does seat then the balance will change (tread package moves outward from center) and you will have a shake.

 

Race tires should be static balanced. Static is a single plane, once per revolution force. As the assembly spins faster the force will be greater. (Try at home - get a rock and string -- spin and speed up spinning).

 

Dynamic balancing goes after couple and static. Couple is equal imbalance 180* apart and goes though the rotational axis. Had to have a magnitude 4-5x greater than that static in the assembly to give a low speed wobble (eg 1oz static would need 5oz pure couple). *Very* unlikely. I had to create a set just to get a feel for it. Its a low speed issue and like I said, takes a lot and 180* apart to do. And if you think about the front or rear suspension -- it cannot move laterally. Not unless the wheel bearings or bushings are bad. Solid rear axle cars cannot have couple issues - assembly is bolted to the axle. Cannot move. (Hint: Mustang OEM spec on balance is static).

 

Static is an up/down and fore/aft motion. Think about your suspension and steering rack. They go up/down and fore/aft. Get fore/aft to phase 180* with 2 assemblies and you get steering wheel nibble. Phase to 0 and you'll bounce the suspension and shake the body, floor, seat.

 

Running too low of cold PSI or not allowing the tires to come up to operating temps will increase slip.

 

Bottom line, static balance the assemblies. Mark for valve location. Allow tire lube to dry before racing. Run correct cold psi.

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You don't balance your race tires!? OK, I am missing something fundamental here.... Can you explain this to me?

 

I can understand that as the tire slips around the wheel, a previously balanced tire will become slightly unbalanced since the tires are probably not perfectly symmetrical (the reason for the balancing weights in the first place, and those weights are attached to the wheel, not the tire).

 

But it still seems to me that you want to at least START with a balanced tire, so that as the tire slips on the wheel, you go from balancing to slightly unbalanced. If you don't balance them at all, aren't you almost guaranteed to have a slight wheel vibration?

 

Just trying to educate myself....

 

I mount them up and go. I've never noticed any vibration bad enough to really annoy me or affect anything

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You don't balance your race tires!? OK, I am missing something fundamental here.... Can you explain this to me?

 

I can understand that as the tire slips around the wheel, a previously balanced tire will become slightly unbalanced since the tires are probably not perfectly symmetrical (the reason for the balancing weights in the first place, and those weights are attached to the wheel, not the tire).

 

But it still seems to me that you want to at least START with a balanced tire, so that as the tire slips on the wheel, you go from balancing to slightly unbalanced. If you don't balance them at all, aren't you almost guaranteed to have a slight wheel vibration?

 

Just trying to educate myself....

 

I mount them up and go. I've never noticed any vibration bad enough to really annoy me or affect anything

 

Hey....don't they also call you Mark "loose lugs" Nunnally???

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While researching how to store tires long term, for a separate thread in the HDPE forum, I stumbled across this document from Nitto:

 

http://www.nittotire.com/Content/pdf/Tips%20For%20Preventing%20TireRim%20Slip%20Vibration%20Complaints.pdf

 

Sounds to me like tire slippage means they weren't mounted correctly, at least not for the high performance application all of us care about.

 

I tried to measure the slippage on my tires during my last track day, but I experienced mechanical problems that cut the day short, so I never really got to put much stress on the tires. I would think Nitto's recommendations here are reasonable, and it would be fair to ask the shop mounting your tires to follow these guidelines.

 

I for one don't think it wise to NOT have your tires road force balanced, and now I see why I keep having to get this redone after every few track days. if the tires were mounted according to these guidelines, the cost savings (by avoiding re-balancing) could be significant. It costs $80-$100 to get a set of 4 tires road force balanced, for example. I'd rather spend that money on track day fees

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it also doesn't take too long to be in this hobby for your own tire mounter and balancer to pay for themselves, esp if you're in an area that you can't get at or below $40/set mounted & balanced

 

... next christmas bonus I'm making that happen for myself...

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it also doesn't take too long to be in this hobby for your own tire mounter and balancer to pay for themselves, esp if you're in an area that you can't get at or below $40/set mounted & balanced

 

... next christmas bonus I'm making that happen for myself...

 

 

Less than $40 a set m&b.......um ...no

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Nitto actually is incorrect. Looks like they don't fully understand how rims and tires mount completely.

 

If you do not lube up the sidewall some you run a very high risk of not seating the bead in the wheel bead wells. For a lot of reasons - not good. The sides to a lot less for rim slip than the toe of the tire. That is the air locking ring and how the tire attaches to the wheel.

 

And the lube should dry quickly in both zones. Unless they are not using the correct mixture (common error to not dilute the pre-mix when its the type that calls for it).

 

I agree on road forcing. Not needed. Road force is radial first harmonic. Completely different issue and type of shake. R1H causes a resonating shake in the body or component attached to the vehicle (steering column, chassis mode, pillar...). R1H appears at 60-70 mph. Its a small window shake that you can drive though. Static is a once per revolution and increases with speed that you cannot drive though. And with sport / r-comp tires with stiff sidewalls R1H is increased due to carcass stiffness - but again, its not an issue since we drive though their shake range so quickly.

 

And a mounting and balance machine will cost you in the 3-10k range for a low end model. Good balance machines go for 12-25k (yes, 3 zeros after those numbers). Really though, if you know how to use a bubble balancer you could DIY with just that (just static).

 

While researching how to store tires long term, for a separate thread in the HDPE forum, I stumbled across this document from Nitto:

 

http://www.nittotire.com/Content/pdf/Tips%20For%20Preventing%20TireRim%20Slip%20Vibration%20Complaints.pdf

 

Sounds to me like tire slippage means they weren't mounted correctly, at least not for the high performance application all of us care about.

 

I tried to measure the slippage on my tires during my last track day, but I experienced mechanical problems that cut the day short, so I never really got to put much stress on the tires. I would think Nitto's recommendations here are reasonable, and it would be fair to ask the shop mounting your tires to follow these guidelines.

 

I for one don't think it wise to NOT have your tires road force balanced, and now I see why I keep having to get this redone after every few track days. if the tires were mounted according to these guidelines, the cost savings (by avoiding re-balancing) could be significant. It costs $80-$100 to get a set of 4 tires road force balanced, for example. I'd rather spend that money on track day fees

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