RE: [A/S] Popping Rivets?

["Oliver Filippi" <ofilippi@xxxxxxxxxxxx>]

Maurice,

The wear on the curb side trailer tires could be a wheel alignment, or even
a bent wheel.  It could also be caused by the crown in the road, especially
on a wide body traveling in the extreme right lane.

So far as tire balancing is concerned, the following are my observations:

Ideally the entire rotating mass (wheels, tires, hubs, and brake drums or
rotors) should be balanced. Realistically the most practical way to do this
is with a spin balancer on the trailer.  But this many not be as good as it
seems at first blush. The problems are threefold.  First, you can't rotate
the tires without re-balancing them.  Second, you must be careful to put the
tire and wheel on in exactly the same position (on the same lug bolts) or
you could have even more imbalance than if you hadn't balance them at all.

The third issue is the superior job modern computer balancers do.  The good
ones are all based on the German Hoffman technology, (industrially, Hoffman
balancers are used to balance all sorts of things, even cutting heads on
high speed woodworking machines) which not only provide a static (rotation)
balance, but also the "dynamic" balance which is important and usually
completely misunderstood.

Dynamic balance has almost nothing to do with the obvious rotation of the
wheel.  Rather, it is the side to side balance from the inside to the
outside of the wheel and tire.  Thus a statically but not dynamically
balanced tire will not rotate on its own in any rotational position, but it
will cause a side to side wobble when it spins.  Typically, on the vehicle
spin balancers do not do a very good job on the dynamic balance.

My gut feeling (though not backed up by any solid facts) is that the off the
vehicle computer spin balance is probably plenty good enough. This assumes
that the rotational (static balance of the hub and drum are not that far
off.  Also, since the diameter of the drum is a lot smaller than the tire,
the impact of a slight imbalance is not going to be that great.

Ideally, the best solution would be to balance the drum and hub independent
of the tire and wheel.  A firm that balances racing engines could probably
do this, but I doubt that it would be worth the effort or cost. [I checked
into this several years ago, and gave up on the idea.]

Some day, perhaps, the companies that make the tire balancers will come up
with an attachment that will allow one to mount just the hub and drum or
rotor on the balancer and thereby balance the hub assembly independent of
the tire and wheel. Then comes the next question - Where you put the
weights?

Oliver Filippi