Hi Guys,
need some help. My bike becomes very unstable when I go over 65-70mph, font wheel starts wobbling and handlebars start shaking. To see what happens I increased my speed to 80 and bike becomes almost impossible to handle. The closest description I can give, it is very similar to when you puncture you front tyre and bike starts zig-zaging??? (closest synonym???). First I thought It was my forks as one was leaking oil. But mechanic sorted that out and problem still there. Also the front wheel has been balanced bearings are fine too. I have knobblies on my wheels, but they are in good condition. Think I only done about 2500miles on them. Middle ones are a little bit more worn than side ones.
If slow down to 60 and less. Bike is fine, but my confidence is going even on short rides. Any suggestions?

Thanks for your help.

Just in case here's a link to the tyre photo

https://picasaweb.google.com/lh/phot...eat=directlink

Vadims