On 6 Jan 2010 17:54:43 GMT, Adrian wrote:

The temperature is only 0 degrees C.

WTF is going on? It can't be black ice. It's not cold enough.

The air may only be 0C but the ground can be several degress lower.
This is why cars fitted with ice warning kit trigger it with an air
temp around 4C. The ground radiates heat and with no cloud cover it
just disappears into outer space and the ground gets colder and
colder. 10 degrees below air temp is very possible. Clouds absorb the
radiated ground heat and radiate it back warming the ground. Not
without losses of course which is why it cools at night.

It's because the rubber in your stone cold tyres is failing to grip the
tarmac properly.

That as well. The tyres I had on until I bought a set of proper
winter tyres(*) had noticeably less grip below about 5C on dry roads,
wet and it was bit dangerous as they became unpredictable. As for
their performance on snow the car might as well have been fitted with
slicks!

(*) Blooming glad I did with 18" of snow outside... Magic, snow
covered 1:7 up hill, no problem. B-)

--
Cheers
Dave.