# Road Force balance numbers different on numerous machines...



## derekjl (Jun 24, 2006)

I initially had my set of Continental tires Road Force balanced when they were new. There was virtually no vibration or noise at any speed. A few months down the road my dealership "accidentally" re-balanced them and despite the use of another Road Force balancer they just weren't the same. I've been to several shops since then and each time the Road Force numerical values have been different on each machine, sometimes different on the same machine. I believe they are currently 19,18,16, and 7. I can definitely feel a vibration in the wheel around 45mph and also at 65mph. Can someone tell me why the Road Force numbers would change from machine to machine? Also, would match mounting these help reduce the numbers and hence the vibration? Thanks.


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## teutoned (Jul 29, 2008)

none of this is the truth... 
road force IS "high tech" match mounting. essentially the balancing machine measures the essentricty of the tire and rim assembly. if it is too out of round, the next step is measure essentricty of rim and match it to the tire for the closest to round assembly. the thresholds for "out of spec" and "in spec" wheel assemblies are adjustable. some shops set the tolerances tight while others have it set loose. tighter tolerances = more out of round assemblies requiring more match mounting... but the #1 cause of different readings is most likely how the wheel is being chucked on the machine. some newer hunter road force machines have a center check option to insure proper/center chucking of wheel to machine. last but not least, when was the machine calibrated last?


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## derekjl (Jun 24, 2006)

teutoned said:


> none of this is the truth...
> road force IS "high tech" match mounting. essentially the balancing machine measures the essentricty of the tire and rim assembly. if it is too out of round, the next step is measure essentricty of rim and match it to the tire for the closest to round assembly. the thresholds for "out of spec" and "in spec" wheel assemblies are adjustable. some shops set the tolerances tight while others have it set loose. tighter tolerances = more out of round assemblies requiring more match mounting... but the #1 cause of different readings is most likely how the wheel is being chucked on the machine. some newer hunter road force machines have a center check option to insure proper/center chucking of wheel to machine. last but not least, when was the machine calibrated last?


 Really appreciate your detailed response. I've heard various opinions on what constitutes a "good" assembly. Some say under 25, some 20, and even 15. It seems that this is one of those cases where a shop could have the best equipment available and not have a staff properly trained on how to use everything. I will ask the next shop to do a centering check on each assembly if their machine has that option.


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## derekjl (Jun 24, 2006)

derekjl said:


> Really appreciate your detailed response. I've heard various opinions on what constitutes a "good" assembly. Some say under 25, some 20, and even 15. It seems that this is one of those cases where a shop could have the best equipment available and not have a staff properly trained on how to use everything. I will ask the next shop to do a centering check on each assembly if their machine has that option.


 My problems are finally solved. Basically the shop turned OFF the "Smart Weight" feature. Apparently this allows for even more precise weight measurement. All of the assemblies were measured for out of round and one tire needed to be rotated 180 degrees. Vibration free now. Hard to drive the car without "expecting" a vibration.


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## derekjl (Jun 24, 2006)

derekjl said:


> My problems are finally solved. Basically the shop turned OFF the "Smart Weight" feature. Apparently this allows for even more precise weight measurement. All of the assemblies were measured for out of round and one tire needed to be rotated 180 degrees. Vibration free now. Hard to drive the car without "expecting" a vibration.


 Just kidding, the vibration is still there. Right when I approach 55mph and up through about 65mph. Although, they were able to get 3 out of 4 Road Force numbers lower by rotating the tires. One of the tires wanted a lot of weight, but already had a low number. It was rotated and took about 1/2 the weight as before, but the Road Force number doubled. I believe the numbers are now 5,7,10, and 18. The 18 is on the LF. This is getting extremely frustrating, to the point I want to buy new tires and maybe even new wheels.


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## Airy32 (Nov 15, 2007)

Before getting new tires/wheels try moving that LF to the rear axle (assuming a square setup and not staggered). The vibration might not be (as) noticeable.


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## derekjl (Jun 24, 2006)

Airy32 said:


> Before getting new tires/wheels try moving that LF to the rear axle (assuming a square setup and not staggered). The vibration might not be (as) noticeable.


 Ok, will try that. Correct me if I'm wrong, but the Road Force numbers and balance are two separate elements? The tire with the high number could be giving a lot more "feeling" in the steering wheel, which can be translated into a vibration even though the tires are perfectly balanced? I might just be investing in Michelin Pilot SS this summer as I hear they are the best thing since sliced bread.


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## derekjl (Jun 24, 2006)

Airy32 said:


> Before getting new tires/wheels try moving that LF to the rear axle (assuming a square setup and not staggered). The vibration might not be (as) noticeable.


Ended up taking it to another shop that is the best in town. There was excessive weight on two of the four wheels. They broke down all the wheels/tires and re-matched them as best as possible. The Road Force numbers are now as follows:

LF - 12
LR - 10
RF - 7
RR - 2

The ride is night and day above what was even not that bad before, but still not "perfect". I had them keep the tires in the same places because I just did my rotation about 2,000 miles ago. If I wanted the minimum vibration placement on my next rotation, where do you suggest the tires go? The tires and non-directional and asymmetric. I would guess a total "X" pattern? Would putting the tires with the highest numbers best be placed on the right side of the car, or both on the rear axles?


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## Airy32 (Nov 15, 2007)

I would suggest always (within reason) putting the higher numbers on the rear axle. Any imperfection will be more pronounced when directly connected to the steering wheel. You might still feel a balance issue through the seat from a rear wheel but it would likely be less annoying than through your hands/wheel.

Although most would probably disagree with my opinion, I stopped worrying about tire rotation years ago. I'm sure there may be some vehicles that it is far more important due to extraordinary wear on one axle or the other. But of the many cars I've owned over the past 25 years I have seen no ill effects from keeping tires on the same axle. When I had staggered sizes I would swap left to right, if I even bothered to pay attention to position at all. As long as my alignment was kept in order, and the wheels were properly balanced (I'm fanatical about these) I never had any unusual wear patterns or issues. With my current car the fronts do wear a bit faster than the rears when driven hard due to being quite nose heavy. If I keep a set of tires long enough to wear the fronts down to the minimum I'll just replace two tires, or sell the rears with tread remaining and replace all four.


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