Just found the oddest thing with my rear tyre - it was a slightly old stock item (Conti Blitz) that was well stored, so after careful inspection I fitted it last year. It was fine during the summer, but when the weather turned colder I started to feel a slight handling oddity when tipping into turns - exactly like loose swingarm or wheel bearings.
Nope, nothing worn I could find. Went over the thing from front to back, and fitted another wheel with new tyre to the front anyway, as the front was about half worn. The new tyre on the front helped, but the wriggle was still there.
By this time the rear was half-worn anyway, so I was beginning to suspect that was the cause, even though it looked perfect and still maintained its profile. With all the bendy roads around here, my tyres never get worn in the middle - they're always worn uniformly across the tread.
Last week I discovered that if I gave the bike some welly around the roads for at least five miles and got the rubber up to temperature, the handling was restored to normal - that odd wriggle totally disappeared.
Looks as though the tyre has gone off and needs to be warmed up a bit to work properly.
"I wasn't riding aggressively or speeding, officer; I was just getting my tyres up to temp."
I'll take that wheel off and keep the rest of the mileage in that tyre for the summer, wear it out then.