I've finally been able to find a shop with the right equipment and knowledge to SOLVE MY LC WHEEL BALANCE ISSUES COMPLETELY! After many, many attempts, I've found a shop that knew exactly what the problem was and walked me though how they solve it...and let me take some pictures. So, here's what I've learned. The LC and a few other Toyotas have a very unique wheel. Most shops just try to position it on a cone-type balancer and let 'er rip. Problem is, with the taper on the front side of the wheel, the cone doesn't exactly fit in the same place every time...yielding a vibration problem that they can chase from now 'till eternity...with no solution. What's needed is a supporting Collet on the back side *and* a finger plate to clamp down on the front side, that locks the wheel securely into place. Here's the pics I took to show what I'm talking about:
Anyways, my LC is now glass smooth at speeds up to 90 (that's as fast as I wanted to go) and the ride is transformed. Yes, they also did run-out and road force balancing & match mounting, but once you get the wheel securely balanced on the machine, the rest is stuff that many other tire shops know how to do. The balancing system the shop I went to can be reviewed in detail here:
(the Precision kit is about 1/3 of the way down)
All the information I shared above shows Hunter products. I'm almost 100% certain that other brands have similar products that work as well - I just didn't see them during my searches. I figured I'd share what I learned because so many tire grease monkeys gave me the eye-roll - you know, "we know more than you, so sit down and shut up and let us do our jobs." Problem was, until now, I haven't found a single shop that really knew how to do their job properly.