Dynamic Wheel Balance - weights on outside?

toyota
corolla

#1

Blockquote’
I just had 4 new Michelin Defenders installed on my 06 Corolla. The shop claims to have performed dynamic balancing on the four tires with OEM steel wheels, but there are no weights on the outside of the wheels, only on the inside lip of the wheels. I am under the impression that a true dynamic balance should require weights on both the inside and outside of the wheel when you have simple steel wheels like these.
Thanks in advance for any thoughts on this.


#2

How many/size weights were used? If not many, then I wouldn’t worry about them just being on the inside.


#3

I agree with you completely.

Odds are, to properly dynamically balance 4 wheels, at least one would have a weight on the outside. I have refused delivery and payment on cars with this condition more than once for exactly what you observed. And I was told that the wheels were dynamically balanced by the service writer. When I insisted, lo and behold at least one wheel of the 4 returned with weights on the outside. Usually 2 or 3.

Tire techs think they are doing you a “favor” by not putting weights on the outside of your aluminum wheels. They are not doing you a favor!


#4

If it needs weight, it needs weight. The only issue I have is that whenever I have had those crimp on weights applied to alloy wheels (factory or aftermarket), this is where the clear coat starts separating first…


#5

OP says original steel wheels. I think where the weights are is not worth worrying about. Also did the OP ask the place that did the work about weight location?


#6

Yeah, that can be a problem, especially if they don’t use the coated weights or if in the rust-belt. That just upsets me much later. Drives me insane right away to have an out of balance wheel soon after having a balance done.


#7

Your impression is incorrect.
If you’re considering the balance of weight between the inside edge of the rim and the outside, remember that the center of gravity of a rim is not centered between the rim edges. It’s somewhere between the surface that sets against the hub and the center of the outer edge of the rim. A wheel’s “offset” places it other than centered between the rim edges.

Also realize that dynamic balancing is designed to compensate for tire irregularities by simulating road forces by pressing a spinning drum against the tire as it’s balance is measured. It’ll compensate for tire out-of-roundness, tire anomalies, and disclose internal tire defects. Its purpose is not to balance the wheel side-to-side. It does so, but a regular spin balance does this as well.

If the car drives smoothly, you’re fine.

Whoops! I almost screwed up!
A dynamic balance is any spin balance.
A “road force balance” is the one with the drum that simulates road forces. Since nobody does bubble balancing anymore, the latter popped into my mind automatically. It’s the better process.
Is the latter what you were referring to as a “dynamic balance”?


#8

About this dynamic balance. How can spinning a wheel/tire at speeds comparable to 80 mph determine whether a weight would be better placed near the inner or outer circumference. All that the machine can do is move and adjust a weight inside the hub the tire attaches to and assign a point and weight value that approximates the results of the machine. While I wasn’t in the tire business it was worthwhile to have everything to mount and balance a tire handy and always used a bubble balancer without any complaints. Even in the 1980s I saw NASCAR tires being balanced on a balancer like mine and don’t recall ever seeing a driver dropping back into the pits for a rebalance.


#9

A dynamic balancer can detect an measure forces lateral to the wheel’s axis as well as radially. Lateral forces can be present in the wheel due to an imbalance between the inside of the rim and the outside of the rim, or from imperfect tires. Note that perfect tires are not normal from a molding process, but good quality tires will be well within operating tolerances and close enough to be readily balanced to where even at high speeds the tires spin smoothly.

A road force balancer can also measure forces placed on the wheel (by tire imperfections such as lack of concentricity and an internal fault ) by its contact with the simulated road.

I remember in the days of bias ply tires when tires that didn’t want to run smooth were “shaved”. There existed a machine with a spinning round cutting blade that could go back and forth and shave the surface of the tire (with the wheel spinning on the machine) to get the tire’s surface as round as practicable. Every tire shop and many garages used to have one, but I haven’t seen one in over 40 years. I doubt if any shop except perhaps a speed shop would have one. Tire manufacturing and tire balancing have evolved to the point where I don’t believe tire shaving machines are necessary any more.


#10

Shaving is still done for situations where for example you have one destroyed tire on an awd car and the remaining three are new enough it makes sense to keep them and shave the new one to match. But not for balancing or truing a tire…