Canada all about tires

The catalyst for excitement in Sunday's Canadian Grand Prix was the unpredictable evolution of the circuit over the weekend.

Tires work by biting into the gaps between the sharp stones in the road surface. When dormant, these gaps are inhabited by moss and detritus. Almost never used, Montreal's Circuit Gilles Villeneuve was, on Friday, the 'greenest' track in recent memory. Furthermore, some corners had been resurfaced with a particularly fine-grained asphalt, offering little traction.

Usually a circuit becomes quicker over a race weekend. It is a living thing - first being cleaned and then 'rubbered-in' as cars circulate. Evolution was delayed in Canada by rain washing away the rubber each evening.