Modern Vespa

My GT is a bit 'screwy' at the moment. She seems twitchy, sometimes in the front, sometimes in the rear??? Things like an over reaction in the steering to a groove in the road and a feeling like the back end isn't going to stick it when cornering.
Some possible factors....
We have had two months of hot sunny weather and the roads a very dry.
My rear tyre is near the end of it's useful life but I am monitoring the tread depth and pressure weekly.
How do you know if the front (or the rear) shocks have had it?
I have been riding a year and a half now...am I getting more confident and at the same time more critical of the GT's handling?

Any discussion welcomed.

Ditch the old tyre. What you describe is exactly how a tyre that has lost its profile behaves. Tyres need replacing long before the tread reaches its legal limit because they square off. The squaring means the bike needs more effort to start to turn, and then will suddenly try and lean too far. If the tyre is near the end of its life it is worth going with that, and if there is still a problem explore further, but I wouldn't try fixing anything else unless you know you have good rubber.

Boulty, I tend to agree with Giuliano - replace the rear tyre. Then see how it measures up. Did mine the world of good when I replaced it and we hit 40 + today in Perth / Fremantle, trust me - I know about "dry" roads.....

Cheers guys
New tyre it is.
Any recommendations?

Just got off the phone with my mechanic.
Metzler ME17 going on at 8am tomorrow morning.
Sweet.

Let us know if it makes a difference mate.