Speed ratings for metric tyres

I finally succumbed to the allure of metric alloys and tyres on the 635, just to see what all the fuss is about.

Hm.

I think the Avon Turbospeed must have a new kind of Z rating: ZWT for Zero Wet Traction. I'd heard all this malarkey about how the 635 is a handful, but on 16" alloys with Dunlop SP8000's, I had no trouble with the car at all. In fact, on a recent cruise, I was actually told the 635 was harder to follow than my Z1 because of the 635's enormous power. All that changed the moment I switched to the metrics. Powerslides in first, second and third; every junction is a new adventure, my life has never run on so much adrenaline before.

Every time I drive to Sainsburys, I feel like the cop in Basic Instinct, knowing that he's tied to the bed with a beautiful psychotic reaching for an ice pick...

Is it just me, is it just the Avons, or are metric tyres certifiable...?