dynamic/spin tire balancing theory

[theKbStockpiler]

I just got back into the auto repair game for a living after a long time. I'm working for a chain I worked for before and it's a flat rate shop. If my own car broke down in their parking lot ,I would have it towed back to my house. Anyways it is a better gig than what I was doing.

Their equipment is almost completely worn out and this includes the tire balancers. Out of 3 of their machines ;2 coasts 1050's and 1 1250 ,only one of the 1050's will do more than a static inside weight only balance on a alloy or dymamically balance a steel rim. They are designed to use a stick on weight behind the spokes for close to a dynamic balance but you have to chase weights for a bout 7 spins to get the balance to go to zero. I made sure that the anchors to the floor were tight and calibrated one of the 1050's. It did not make a difference but it got me thinking.

A static tire balance offsets extra or needed weight based on basically one half of the tire compared to the other half. Otherwise some times the machine would ask for more than one weight on one side if you are using clip on weights. It is most likely that tires and rims are not imbalanced in a small section but gradually over a large portion of the tire so one heavy weight in one place can offset an imbalance over a larger area on the other side (top or bottom). Two smaller weights spaced apart would actually be better.

Dynamic balancing comes in when the static imbalance is not in the center or is on one side or the other. If the imbalance is on the inside where the clip on weight is there is no dynamic imbalance so it's fine but if the imbalance is on the opposite side (inside or out side of rim) it will be dymanically imbalanced.

My point here is that even with a dynamic spin balancer the tire is not really perfectly balanced unless you consider the tire as having only two sides and not being circular.

[saltracer]

When I worked in shops, I only ever static balanced my own tires so there was only weights on the inside of the rim. Did it that way for years and never had a problem with vibrations on the highway

[Ol'fogasaurus]

Back in the late '50s, when we were running only bias tires, most places (like I worked at) had "bubble balancers". Some of the high end shops had spin balancers' which were just becoming the rage.

On the weights in some cases they were on the outside of the rim but in other cases (wide or off-set rims usually) we split the weights and put them on the inside and outside of the rim to even the balance out. Later they came out with weights with tape or something like that on them and we often put them on the rim by the mount portion of the rim to keep the balance centered.

One of the tricks back then was to mount and balance the tires then drive them for a couple of miles doing turns and things to ensure they were fully set then pull them back off the car and had a machine that would rotate the tire and as it rotated the machine would slice off some of the tire's tread so as to be sure the mounted tire was round. Some also made kerf like cuts in the treads (I forget the name of that now) but it seems like I heard that that lasted for a long time and as far as I know it might still being done.

I just did a check on todays techniques then did a search on balancing scams and yup, same techniques, different techniques and scams are still going on. Balancing itself still has a lot of personal opinions on it.

Lee

[Ol'fogasaurus]

Back in the late '50s, when we were running only bias tires, most places (like I worked at) had "bubble balancers". Some of the high end shops had spin balancers' which were just becoming the rage.

On the weights in some cases they were on the outside of the rim but in other cases (wide or off-set rims usually) we split the weights and put them on the inside and outside of the rim to even the balance out. Later they came out with weights with tape or something like that on them and we often put them on the rim by the mount portion of the rim to keep the balance centered.

One of the tricks back then was to mount and balance the tires then drive them for a couple of miles doing turns and things to ensure they were fully set then pull them back off the car and had a machine that would rotate the tire and as it rotated the machine would slice off some of the tire's tread so as to be sure the mounted tire was round. Some also made kerf like cuts in the treads (I forget the name of that now) but it seems like I heard that that lasted for a long time and as far as I know it might still being done.

I just did a check on todays techniques then did a search on balancing scams and yup, same techniques, different techniques and scams are still going on. Balancing itself still has a lot of personal opinions on it.

Lee

The term I was trying to remember is tire siping and it is still done. It supposedly improves traction: For what it is worth: https://www.bing.com/search?q=siping+ti ... 7cea257d2c

[andy198712]

Like snow tyres?

[Ol'fogasaurus]

Like snow tyres?

I have never done it but if you read the Consumer Reports report it sounds like it is an honest discussion on the topic.

Since I don't play around on the street and carry traction even for my 4WD rigs as cover for the usually limited snow we get here (the street I live on is so steep at the bottom it is usually barricaded when more than a couple of the inches of the white stuff when it falls). As I said, I didn't know if it was still being done and was surprised that it was.

Lee