bigEL

OK, so I've had a set of Blizzaks on steelies for about 5 years now. At most, I may put 1500-2000 mi on them each winter. Snow tires aren't wear rated, so I don't know how much life is left but they still have 10-11/32 tread left on them and look pretty much new. Anyway, my problem is that they worked beautifully for the first couple years. But for the last 3 years, I notice a shimmy between 50-70 mph. First time it happened, I thought they developed flat spots from being stored on their sides and would round out with some driving. But when it didn't go away, I got the alignment, brakes, and tires checked. The only thing they found was a slight imbalance in 1 tire. This was on a Road Force machine. The tires ran perfectly smooth for the rest of that winter. I thought the imbalance might be due to them being stacked on their sides, even though I store my summer tires the same way with no problems. So at the end of that winter, I stored them on their sides, but spread out, not stacked. But the following winter, the shimmy comes back. This time, 2 of the tires are out of balance. After rebalancing, the shimmy goes away. So last year, I decided to store the tires upright. But, guess what? This winter, they are out of balance again. Anyone else have this problem? Any ideas why it is happening or how to solve it other than rebalancing my tires each year? I do mark the tires and rotate them front-to-back each time I have them installed.