CHINA DAILY - Canada all about tyres

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

Tyres 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.

For racing tyres to work effectively they must be hot. Pre-heated to about 80-degrees centrigrade, they lose temperature when moving at speed through the air. Heat is generated effectively only if the tyre grips the road surface such that the tyre carcass flexes under lateral load. Some warmth comes from the brakes (which operate at several hundred degrees) but it is the compression and expansion of the rubber which is critical.

Skimming across Canada’s low-grip track the tyres remained frigid and unbending. Worse the rubber was torn by the road and rolled up on the tyre surface - a phenomenon called ‘graining’. The Montreal track has a number of ‘traction events’ - acceleration from slow bends - so rear tyres suffered most.

The regulations allow only two tyre compounds. Choice is free within a restriction on total sets used but those in the top 10 grid positions must start the race on the compound used to set their qualifying time. Everyone must use both types during the race - hence pit stops continue despite this season’s ban on refuelling.


Paradoxically it was the super-soft ‘option’ tyres which suffered most in Canada. They were not sufficiently grippy to generate heat before the rubber was damaged. The medium-grip ‘prime’ tyres took longer to ‘switch-on’ to working temperature but were resilient to damage.

Concerns about degradation in the race led both Red Bull drivers (and Renault’s Robert Kubica) - uniquely this season - to choose the harder tyre for their final qualifying runs. The soft tyres on Lewis Hamilton’s pole-starting McLaren were ruined by lap seven, but not long after the prime-shod cars were also in the pits and lost any advantage.


Thereafter everyone was in the same boat: restrained from outright speed by fragile tyres. Track position and mature driving gave Hamilton, in the end, a commanding win but the Canadian GP was a classic because - as in wet conditions - the playing field was levelled by reduced grip.