Inaccurate wheel balancing - has any1 here experienced this ?
 

"Juhan Leemet" wrote

> > I can't imagine a modern tire, particularly the newer lower profiles changing
> > diameter at high speed enough to affect the balance of the tire/wheel assembly.
>
> I recall seeing some film showing the changes in shape of a tire at speed.
> The outer surface of the tire had a kind of scalloped shape, definitely
> NOT a smooth, round circle. It looked like there were some kind of surface
> waves rippling along the outer surface.

Yep, considering that at 60-mph (car speed) each part of that flexy rubber tire
has to go from 0 (on the road surface) to 120 (top of tire) and back to 0, about
13 times per second. All that centrifugal force is going to do strange things!

> If there is that kind of
> distortion in the shape of the tire, then any arguments about grams of
> weight here or there are likely moot. I suspect the balance of a tire
> rolling along the ground may not be that precise? Best approximation kind
> of thing? OTOH, I do not recall what kind (radial?) of tire in the film.

And of course, wheels aren't perfectly round, neither are tires, and most
tires will have slightly stiffer sections where the belts are overlapped during
manufacturing. Not only will the stiffer parts not flex the same when they hit
the ground, they won't stretch away from center as much at that 120mph
"top of the circle" either, both of which can cause vibrations or seemingly
(as the thread is named)... "Inaccurate wheel balancing".