Something that I'm sure enters into the equation is tire growth. They may look round in the static condition, all of mine were but who knows what happens when they are up to speed. An extreme example of what I’m talking about is what you see on the dragster tires. All be it on a much much smaller scale, I'm sure you would see the same thing happening to a street tire. That was the reason I had both sets (bias & radial) of tires spun up on a road force balancer.
Resonance can be just prevalent and just as confusing in mechanics as it is in electronics, music or any other science. No matter what you do to a tire it’s gonna have a tiny bit of out of balance the will show its face as you pass thru it’s critical speed. This can resonate with other things like the springs, frame, a body part or engine-driveline part and the vibration will be amplified. I think that is the only explanation for some of the weird vibrations that are encountered in a vehicle.
There were a lot of these nodes in the aerobatic airplane I built and flew. But just as there is in any vehicle that I’ve ever driven, there is that sweet spot where every thing feels just right.
I’m always up for trying something new and I would like to locate a shop and see if they could true up those Power King bias ply’s any more than they are. They only had a thousand or so miles on them when I took them off the ’50. The ’54 needs tires before I can drive it, the skins that are on there now were installed in 1988. So I’d like to try them on that truck and see if I get the same period of vibration at the same speed as I did in the ’50. Only problem is I’m still gonna have to put up with that dang flat spotting when I wake her up in the morning.
Denny Graham
Sandwich, IL
