Tire Balancing

[Grandpot]

Tire balancing has been mentioned before, but I just wanted to add my $.02. I own an automotive repair shop and teach the repair of precision machinery at the local technical college, so I have a reasonable handle on the subject.

Things to consider: tire roundness, radial balance, lateral balance, side wall strength, and tire belt damage.

1. ROUNDNESS: A tire can be balanced and still give a rough ride if it is not round. The highest out of round condition on a car tire is around .080". Due to the light weight of a Spyder, I would keep this to .040" or less. You can measure this by jacking up the Spyder and spinning the wheel. Place something that won't easily move against the tire tread at its highest point and then turn the tire until you see the lowest point. Measure the gap. This also needs to be done on the side wall. The tire needs to be round and not wobble.

2. RADIAL BALANCE: This is what people normally perceive as balancing and it is what you get when you STATIC balance a tire. It will counteract the out of balance condition of a tire at the tread due to uneven densities. This will cure tire HOP, as long as the tire is round.

3. LATERAL BALANCE: If you are experiencing tire SHIMMY, tire wobbling left to right, you most likely will need a lateral balance. This is due to uneven densities from the left side of the tire and wheel to the right side of the tire and wheel. As the tire rotates, it throws itself side to side instead of hopping. Not all balancing machines will detect a lateral imbalance condition, so be very specific and ask the technician if his machine has this capability. Some technicians that do not have a machine that can measure lateral imbalance will put and equal amount of weight on the left side and right side, assuming this will work. Rarely will the required weights be equal left to right. I just balanced a tire and put 1.5 ounces on the inside of the rim and .5 ounce on the outside. Before doing this kind of work, be certain the steering linkage is in good condition and not sloppy.

4. SIDE WALL STRENGTH: This has to do with the evenness of the tire sidewalls. As you go around the tire and the side wall thickness varies, most likely the strength of the side wall will vary. When riding you will feel like you are on uneven springs as the tire rotates. The tire can be perfectly round, balanced, and look normal, but you will still get a bouncy ride. You will notice it more when driving slow. A balancing machine with TIRE FORCE capability can detect this. Not all machines can measure TIRE FORCE. The only cure is to get a new tire.

5. BELT DAMAGE: If your Spyder waddles like a duck when moving slow, most likely you have a broken tire belt or slipped belts. I am talking about the layers of belts inside the tire, not the drive belt. Replace the tire.

I hope this clears up some mysteries of tire balancing.

[SNOOPY]

Nice write up

[STELLING MAN]

Very enlightening, thanks for that writeup..

[Pennyrick]

Thanks... informative post.

I can recall many years ago reading an article by Tom McCahill (the dean of road testers back in the day) in the old Mechanic Illustrated magazine on this subject.

Tom's observation was that the best way to guarantee good tire life and performance was to get the tire dealer to go through his inventory and find tires that were 'ROUND". His guess was that more than half of the stuff being sold failed the roundness test. Of course he was being facetious but it is still probably true today.

[GreenDragon]

Nice write up. Should be basic information, but sadly is not well known.
what can you tell us about laser alignment?

[Chupaca]

thanks for this informative post. Explains a lot and hope all get a chance to see it...

[Little Blue]

YES, All very Good Information. As someone else posted here. Do You Have Any Info on Laser Alignments?

[SPECTACUALR SPIDERMAN]

radial run out of passenger/LT tire is 0.026" i prefer keeping it under 0.015", for my spyder i want to keep it
under 0.012".
these are the run outs i use for road force balancing on the assembly.

[Grandpot]

YES, All very Good Information. As someone else posted here. Do You Have Any Info on Laser Alignments?

Sorry, nothing about lasers.

[Motorcycledave]

I am also a "former 20 years, automotive repair shop/tire and wheel/alignment owner
and have addressed this as well, as you have, This is the real information not some BS from a sales guy
out of round and other factors are all needing to be checked. Damn I just checked ... I am turning into an OLD guy....

Tire balancing has been mentioned before, but I just wanted to add my $.02. I own an automotive repair shop and teach the repair of precision machinery at the local technical college, so I have a reasonable handle on the subject.

Things to consider: tire roundness, radial balance, lateral balance, side wall strength, and tire belt damage.

1. ROUNDNESS: A tire can be balanced and still give a rough ride if it is not round. The highest out of round condition on a car tire is around .080". Due to the light weight of a Spyder, I would keep this to .040" or less. You can measure this by jacking up the Spyder and spinning the wheel. Place something that won't easily move against the tire tread at its highest point and then turn the tire until you see the lowest point. Measure the gap. This also needs to be done on the side wall. The tire needs to be round and not wobble.

2. RADIAL BALANCE: This is what people normally perceive as balancing and it is what you get when you STATIC balance a tire. It will counteract the out of balance condition of a tire at the tread due to uneven densities. This will cure tire HOP, as long as the tire is round.

3. LATERAL BALANCE: If you are experiencing tire SHIMMY, tire wobbling left to right, you most likely will need a lateral balance. This is due to uneven densities from the left side of the tire and wheel to the right side of the tire and wheel. As the tire rotates, it throws itself side to side instead of hopping. Not all balancing machines will detect a lateral imbalance condition, so be very specific and ask the technician if his machine has this capability. Some technicians that do not have a machine that can measure lateral imbalance will put and equal amount of weight on the left side and right side, assuming this will work. Rarely will the required weights be equal left to right. I just balanced a tire and put 1.5 ounces on the inside of the rim and .5 ounce on the outside. Before doing this kind of work, be certain the steering linkage is in good condition and not sloppy.

4. SIDE WALL STRENGTH: This has to do with the evenness of the tire sidewalls. As you go around the tire and the side wall thickness varies, most likely the strength of the side wall will vary. When riding you will feel like you are on uneven springs as the tire rotates. The tire can be perfectly round, balanced, and look normal, but you will still get a bouncy ride. You will notice it more when driving slow. A balancing machine with TIRE FORCE capability can detect this. Not all machines can measure TIRE FORCE. The only cure is to get a new tire.

5. BELT DAMAGE: If your Spyder waddles like a duck when moving slow, most likely you have a broken tire belt or slipped belts. I am talking about the layers of belts inside the tire, not the drive belt. Replace the tire.

I hope this clears up some mysteries of tire balancing.