How Can Tire Uniformity Parameters Help Improve Tire Balancing?

[ahghshirazi]

my question

in tire industry except dynamic unbalncing ( gr.cm2) and static unbalancing (gr.cm )other tire speccifications like RFV(radial force variation), LFV(latral force variation) , CON(conicity) is evaluted as tire uniformity in tire uniformity machine.
is it possible to find some formla to express unbalncing according to tire uniformity parameters or its component like first harmonic of radial force variation?
thanks in advance.

 

[Ranger Mike]

probably not. if tires are made like we make race tires in Indiana, the test results you noted are dynamic and made after post process inflation. I highly doubt this test will provide suitable data to determine condition of balance. here is why..
during a stock car race, we need to maintain a proper tire diameter once the tire is brought up to proper operating temperatures. usually 180 to 210 degrees F. depending upon the weight of vehicle and particular tire compound. in order to maintain the proper diameter, we use nitrogen instead of air because this gas dies not have moisture in it, has large molecules and will not bleed through the tire wall. the lack of moisture means the tire will expand at a more consistent rate vs. moisture rich air which could steam up on you.
we found a very odd occurrence one time at the race track. we measured the tires before the car went out. after several "hot laps" the car came in and we again measured the tires..the diameter was significantly SMALLER than before the hot lap session...can anyone guess why this happened?

 

[Ranger Mike]

I will attempt to answer the initial question. imperfections in the manufacture of wheels , steel, magnesium, aluminum...no matter how close a manufacturing process is monitored, will still yield wheels that are out of balance. only when the tire and wheel are properly assembled, and the tire is inflated to proper setting , can the assembly be balanced to remove the out of balance condition. granted, the better each component is manufactured to a perfect standard, the less weights required to remove the out of balance condition. but when one is making one million wheels a year and like number of tires, a practical compromise must be made from the sheer economics of the situation. the answer to my former question may throw more light on this.