I recently replaced the tires on my 86 Aspy with a set of Avon Cobras, as the old (really old) Elite II's were worn and out dated. I installed the front first, which made a world of difference. The bike actually felt kind of sporty. I then replaced the rear, about a week later. They felt pretty good for a few days, then I started getting a bit of a wobble when cruising about 70. It was akin to a less extreme version of the Keystone Cops, as if the wheel was warped. If I back off on the speed a little, it goes away. I went back through and rechecked my axle caps, axle nuts, and brake components to insure they were properly aligned and torqued. All looks good there.
I find it hard to believe the rear tire would wreak that much havoc by itself, but stranger things have happened. As I said, this didn't occur until I mounted the rear tire, and never before with the old tires. I hate to think I may have to change to a different rear just to get it corrected. Since I'm off tomorrow, I'll take a look at the head bearings and try and service the front forks.
This is a little nerve racking, as I'm getting my wife back into riding and just don't feel good about putting her on the back until I get this fixed.
Thanks in advance.