I'm getting a shimmy in my Sedona over 73 mph lately. Thing is, I had all 4 wheels Road Force balanced last July, so roughly 11 months ago. Tires are General Altimax RT43s, FWIW, with about 34,000 miles on them. When I had them balanced last year, two of the wheels were quite a bit out of balance, despite the fact that they had been balanced less than a year before also. I do know that one of my wheels is slightly bent, but I think that's been the case for pretty much every vehicle I've ever owned. Prior to this van, I've never had to re-balance wheels once I've had tires installed; not until the tires wore out and new ones were put on. So are some tires prone to needing re-balancing more often? If they keep doing this, I'd rather just buy new tires than have to keep re-balancing.