Wheels balanced to "00"

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tc1446

tc1446

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Had new tires put on an '05 Mercedes yesterday and watched the tech balance the wheels. After he had placed the weights on the two spots indicated he spun the wheel again to check balance and each time he got double Zeros for both weights. Don't know what the norm is, but I was impressed that he took the time to check his work. I have seen techs that don't do that and sometimes the wheel wasn't balanced right. I made sure he was rewarded for his work.
 
That is what they are supposed to do. I would always spin to confirm. There is a setting on the machine to give exact numbers as opposed to rounding off to the closest .25oz. When I was at Sears my friends that worked there and I had a game to see who could get closest to 00 with the rounding turned off. You would be amazed how many complaints we got because we took longer to make sure we did our jobs right.
 
The problem with balancing in the coarse mode display, is with 0.0, instead of using fine mode of 0.00oz, the wheel can be over .5oz out of balance when the dynamic residual imbalance lines up, creating a static imbalance. In fine mode you can see that easily because it will display 0.05oz increments on either side of the wheel. You can move a weight less than a 1/4 of an inch and see the display change by .05oz. You have to get the static imbalance as low as possible, more so than the dynamic. When I balance using tape weights, it can take over a dozen spins to dial it down. That's is what I have experienced. You don't have to have a road force balancer to do it right, but that would surely help in a few cases.
 
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I'm with Traction on this. I have a Corghi EM43 for my personal garage and I set it to the most sensitive setting and do my measurements. Once I'm done I dismount the wheel from the machine and reinstall it and spin once again to ensure that it's balance properly. I do my car tires every 10,000 miles and they usually do require rebalance at this interval.
 
What studies I have seen say that the vast majority of vehicles are insensitive to anything under 1/4 oz. (5 grams) - that for practical purposes, the normal round off error built into balance machines due to the increments of the weights available is more than adequate. Just an FYI: If the machine rounds off to the nearest 1/4 oz. (5 grams), it is getting the tire and wheel assembly within 1/8 oz (2 1/2 grams) - and as I indicated, studies say that is more than adequate. OK, so for those who are interested in how they do these studies: They take a typical vehicle, then mount 4 completely balanced and zero runout tires on it. They ride the vehicle and rate the ride. Then add balance weights and ride the vehicle after each weight addition - until the ride quality changes. They do this randomly and on different wheel positions so the guy rating the ride has no idea what he is riding on. They then develop an equation for the vehicle that shows how much affect this has, and what the worst case would look like. Hopefully that worst case indicates that the specs don't need to be adjusted.
 
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Originally Posted By: CapriRacer
What studies I have seen say that the vast majority of vehicles are insensitive to anything under 1/4 oz. (5 grams) - that for practical purposes, the normal round off error built into balance machines due to the increments of the weights available is more than adequate. Just an FYI: If the machine rounds off to the nearest 1/4 oz. (5 grams), it is getting the tire and wheel assembly within 1/8 oz (2 1/2 grams) - and as I indicated, studies say that is more than adequate. OK, so for those who are interested in how they do these studies: They take a typical vehicle, then mount 4 completely balanced and zero runout tires on it. They ride the vehicle and rate the ride. Then add balance weights and ride the vehicle after each weight addition - until the ride quality changes. They do this randomly and on different wheel positions so the guy rating the ride has no idea what he is riding on. They then develop an equation for the vehicle that shows how much affect this has, and what the worst case would look like. Hopefully that worst case indicates that the specs don't need to be adjusted.
I agree, only thing is there are 28grams in an ounce, your math suggests 20.
 
Originally Posted By: CapriRacer
What studies I have seen say that the vast majority of vehicles are insensitive to anything under 1/4 oz. (5 grams) - that for practical purposes, the normal round off error built into balance machines due to the increments of the weights available is more than adequate. Just an FYI: If the machine rounds off to the nearest 1/4 oz. (5 grams), it is getting the tire and wheel assembly within 1/8 oz (2 1/2 grams) - and as I indicated, studies say that is more than adequate. OK, so for those who are interested in how they do these studies: They take a typical vehicle, then mount 4 completely balanced and zero runout tires on it. They ride the vehicle and rate the ride. Then add balance weights and ride the vehicle after each weight addition - until the ride quality changes. They do this randomly and on different wheel positions so the guy rating the ride has no idea what he is riding on. They then develop an equation for the vehicle that shows how much affect this has, and what the worst case would look like. Hopefully that worst case indicates that the specs don't need to be adjusted.
The problem is, in rounding to 1/4oz, the assembly can be up 1/2oz off, and read zero on the display. 4 tires that are .5oz off could be an issue with some vehicles.
 
Originally Posted By: Olas
Originally Posted By: CapriRacer
What studies I have seen say that the vast majority of vehicles are insensitive to anything under 1/4 oz. (5 grams) - that for practical purposes, the normal round off error built into balance machines due to the increments of the weights available is more than adequate. Just an FYI: If the machine rounds off to the nearest 1/4 oz. (5 grams), it is getting the tire and wheel assembly within 1/8 oz (2 1/2 grams) - and as I indicated, studies say that is more than adequate. OK, so for those who are interested in how they do these studies: They take a typical vehicle, then mount 4 completely balanced and zero runout tires on it. They ride the vehicle and rate the ride. Then add balance weights and ride the vehicle after each weight addition - until the ride quality changes. They do this randomly and on different wheel positions so the guy rating the ride has no idea what he is riding on. They then develop an equation for the vehicle that shows how much affect this has, and what the worst case would look like. Hopefully that worst case indicates that the specs don't need to be adjusted.
I agree, only thing is there are 28grams in an ounce, your math suggests 20.
I suppose in metric mode 5 grams is the lowest reading worthwhile to report. Is its weight just a stamped piece of sheet metal?
 
Originally Posted By: FowVay
I'm with Traction on this. I have a Corghi EM43 for my personal garage and I set it to the most sensitive setting and do my measurements. Once I'm done I dismount the wheel from the machine and reinstall it and spin once again to ensure that it's balance properly. I do my car tires every 10,000 miles and they usually do require rebalance at this interval.
Interesting. I've never rotated tires, nor have I ever needed to rebalance them. Our 2006 Subaru Outback just went 102,000 miles on a set of tires that were never rotated, and the only time they were balanced was when they were originally installed. There was no issue with them, and the only reason they were replaced was because of age. What is it about your tires/vehicles that causes problems every 10,000 miles?
 
I can usually start to feel imbalance on the front when it gets to about .75oz off and higher. Under that, Ive never felt. When I worked at TLE, I would sometimes turn off rounding whenever the stupid machine wanted me to chase weights, which was often.
Originally Posted By: eljefino
I suppose in metric mode 5 grams is the lowest reading worthwhile to report. Is its weight just a stamped piece of sheet metal?
Yes, in metric mode they typically use 5 gram increments. And the 5 gram weights are like current .25oz weights, just a piece of steel stamped with the weight.
 
Originally Posted By: Traction
The problem is, in rounding to 1/4oz, the assembly can be up 1/2oz off, and read zero on the display. 4 tires that are .5oz off could be an issue with some vehicles.
Uh ...... Mmmmmm ..... Not exactly. Think of it this way. If I have a tire and wheel assembly that needs 3 grams to balance, the machine will call for 5 - meaning that adding the weight will cause the assembly to be off 2. If the assembly needs 7, the machine will also call for 5 - meaning the assembly will again be off by 2. Try that for every value between 3 and 7, and the machine will call for 5 grams. But below 2 1/2 gr and above 7 1/2 grams, the machine will call for some other value - meaning the assembly is always within 2 1/2 grams.
 
Originally Posted By: Pop_Rivit
What is it about your tires/vehicles that causes problems every 10,000 miles?
It is irregular tire wear. Even small amounts of misalignment cause the tires to wear irregularly - and, of course, the greater the misalignment, the faster the tire wears and the more irregular the wear becomes. What causes the tires to wear irregularly rather than rapidly, but uniformly? I don't know, but I did see some research that says that higher harmonics of force variation plays a role here - on the order of 10th to 20th harmonics. I'll bet that vibration modes also play a role - and I can not begin to tell you all the ways tires can vibrate. Not just up and down, but side to side, tangentially, and countless combinations of all of those. And what about alignment? Well, not only is it impossible to get an alignment that is EXACTLY right for every possible situation, but there are just sooooo many variables that I think even an active adjustment system for alignment wouldn't quite get them all. It might help on the big ticket items, so there is hope that the future will be better.
 
Originally Posted By: CapriRacer
Originally Posted By: Traction
The problem is, in rounding to 1/4oz, the assembly can be up 1/2oz off, and read zero on the display. 4 tires that are .5oz off could be an issue with some vehicles.
Uh ...... Mmmmmm ..... Not exactly. Think of it this way. If I have a tire and wheel assembly that needs 3 grams to balance, the machine will call for 5 - meaning that adding the weight will cause the assembly to be off 2. If the assembly needs 7, the machine will also call for 5 - meaning the assembly will again be off by 2. Try that for every value between 3 and 7, and the machine will call for 5 grams. But below 2 1/2 gr and above 7 1/2 grams, the machine will call for some other value - meaning the assembly is always within 2 1/2 grams.
I was referring to the residual static imbalance can be double, if in your case you could have 2 1/2 grams of imbalance in dynamic mode, but the static mode could be 5 grams off if the 2 1/2 grams added together from inside and outside. When using fine mode on the balancer you can see that. The outer plane could be .2oz and the inner plane .2oz, and if they line up, you can switch to static mode and it will show .4oz.
 
Originally Posted By: Traction
I was referring to the residual static imbalance can be double, if in your case you could have 2 1/2 grams of imbalance in dynamic mode, but the static mode could be 5 grams off if the 2 1/2 grams added together from inside and outside. When using fine mode on the balancer you can see that. The outer plane could be .2oz and the inner plane .2oz, and if they line up, you can switch to static mode and it will show .4oz.
I don't think it works that way. The machine will call for weights such that the amount of residual imbalance can not be corrected with the available increments - so the residual imbalance would be at worse half the increment - for both static and dynamic.
 
Originally Posted By: CapriRacer
Originally Posted By: Traction
I was referring to the residual static imbalance can be double, if in your case you could have 2 1/2 grams of imbalance in dynamic mode, but the static mode could be 5 grams off if the 2 1/2 grams added together from inside and outside. When using fine mode on the balancer you can see that. The outer plane could be .2oz and the inner plane .2oz, and if they line up, you can switch to static mode and it will show .4oz.
I don't think it works that way. The machine will call for weights such that the amount of residual imbalance can not be corrected with the available increments - so the residual imbalance would be at worse half the increment - for both static and dynamic.
It can double the static when the inner/outer dynamic imbalance lines up. If the dynamic imbalance inner/outer is 180 degrees apart, only then can you achieve zero static balance. Balanced thousands of tires, and that is I have seen anyway. I also cut tape weights to get smaller increments. Of course 1 pebble stuck in the tire will throw it off. I always try to get the lowest reading possible on the balancer anyway.
 
Originally Posted By: Traction
It can double the static when the inner/outer dynamic imbalance lines up. If the dynamic imbalance inner/outer is 180 degrees apart, only then can you achieve zero static balance. Balanced thousands of tires, and that is I have seen anyway. I also cut tape weights to get smaller increments. Of course 1 pebble stuck in the tire will throw it off. I always try to get the lowest reading possible on the balancer anyway.
To be nice about it, I think you are wrong, but I am not willing to take the time to prove it. Let's just leave it as an "agree to disagree".
 
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