On Sun, 13 Dec 2015 21:05:30 -0800, The Real Bev
wrote:


For example, almost *never* when I look at car tires in the Costco
parking lot with brand new tires, is the dot in the correct place.

Dot? Explain...


They are basically marks on tires which are supposed to indicate
"balance points." A red dot represents radial runout, a yellow dot
represents the "light" spot of the tire.
You're supposed to mount the tire with the dots aligned with the wheel
stem hole, or the "low spot" dimple - if present - on a steel wheel.
If you have both red and yellow dots, ignore the yellow.
This might give you a chance of finding the best initial balance point
- if you're lucky. Depends of how accurately the wheel and tire were
manufactured and tested in terms of "balance" and runout.
But if you balance tires with a Hunter Road Force balancer, which is
how I get my tires balanced, the dots end up at random locations.
If I was bubble-balancing my own tires, I'd use them.
My kid worked mounting tires at Just Tires for a couple years and when
I mentioned the dots to him he responded with, "Oh yeah, I noticed the
dots sometimes. Didn't know what they were for. Interesting"
And some tire manufacturers don't mark their tires with balance
points.