I have been spending some time at Autopia and I posted these photos there and they have created a lot of interest in a product we get in Australia but is not available in North America.
The product is "Polyglaze Tyre Black", a water based paint for tyres and the finish lasts for months, as long as you don't touch a kerb/gutter. It dries completely and will not wash off or of course sling off.
Apologies that it is not being displayed on a 300C, you probably all have read that I am waiting for local release here later this year.