Road Force?

[Bobster]

Any one out there have a handle on the physics behind the "road force" numbers and what they mean?

Just completed a 15K mile checkup and the dealer said I had excessive "road force" in three tires. It's been a while since I've had to worry about tire balancing. So, the term "road force" caught me a little off guard. I was told normal is less than 18 something and that my tires were as much as 30. Did I notice any vibration?

No, the tires rode OK to me. Tires were rotated. They still ride OK. The dealer said that they might give me trouble as they wear.

The dealer tried to explain the difference between balancing and road force. Something to do with the weight of the vehicle as the tire rotated? Could it be due to flat spots caused by the vehicle sitting for some time?

Thanks

[Eckstream]

Sounds like hes takin you for a ride.... It might be the tires ability to carry a heavier load like towing. Did he try to sell you something to correct this problem?

[Bobster]

No, he did not try to sell me anything. He just wanted to let me know they found a problem with three of the tires. And, did I notice a vibration? Which I did not.

[Daver]

Road Force is a trademark from the Hunter brand of balancing machines.

It's a measure of how round your wheel and tire are while under load.

So balancing is about making sure all four tires match in weight, and road force is about how round each individual tire is while mounted on a wheel.

-Daver

[skunkworks]

Yes, ideally for a car the road force should be 15 or under and for pickup and suv's it should be under 24 lb. With the Hunter 9700 balancer it shows you how to turn the tire on the wheel to get the lowest combination.
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[autox-racer]

I found this via google... on tire rack... basically sounds like you need to watch how your tire wears and only worry about it if you feel a vibration or excessive tire wear.


The GSP9700 Vibration Control System includes Hunter's exclusive Road Force Measurement System to help detect potential tire uniformity causes of vibration that are not balance-related. This system utilizes a "road roller" which applies up to 1,400 pounds (635 kg) of force against the wheel and tire assembly to measure their combined uniformity. This simulated road force test helps verify if the assembly is "round" when rolling under load.

tire rack article (http://www.tirerack.com/wheels/tech/ride_uniformity.htm)