A little more food for thought.
I've looked at a bunch of rims over the last few weeks, on a bunch of trucks and have
yet to find one that has any markings/notches/scratches/dimples on them. I have read
that sometimes the manufacturer will put a sticker on them indicating the low point,
which is usually removed once the tire is mounted. As I said, I found no dimple
but I did happen to find a sticker still on one front wheel of my 2014 Silverado:
http://www.pbase.com/dennygraham/image/160256437/original The rest are missing off the rims, but I now feel a bit more confident that the factory did
match-mount the tires.
If only I knew that the ones on the ’50 were matched, which I’m sure they are not. Even
though the tire shop road-force balanced them the last time, I’m sure they didn’t
dismount them to rotate them.
Here’s a quote from the Bridgestone tire company:
“Can we review which dot goes where? First, if the tire has a red dot, ignore the yellow
dot. Then, if you have a steel wheel, look for the low point dimple on the wheel, and
mount the tire with the red dot next to the low point dimple. If the wheel is aluminum, or
if it’s steel, but has no low point dimple, mount the tire with the red dot next to the valve
stem.”
And this quote, again, from that Bridgestone site, may explain why I’m getting the
40mph hop, which if allowed to continue for a minute or so, can actually build in
amplitude as a harmonic vibration can do.
“OK, that makes sense for the yellow dot, but what about the red dot? The red dot is
much more complicated than the yellow dot. It indicates the “radial force variation first
harmonic maximum.” That’s a mouthful, of course, but it’s a way of indicating where the
centrifugal force tending to pull the rotating tire away from the wheel is greatest. Another
way of looking at it is that in a sense, if the tire were out of round, the red dot would
more or less correspond to the “high point” or place where radial runout forces are
greatest.”
Denny Graham
Sandwich, IL
