Pirelli: Rain expected for Chinese GP qualifying 18 April, 2014 89 Weather will have a big effect on tyre behaviour throughout the Chinese Grand Prix weekend, with Free Practice today characterised by cool weather, and a possibility of rain for Qualifying tomorrow. Ambient and track temperatures dipped to 13 and 15 degrees centigrade respectively during FP1 this morning, before becoming slightly warmer in the afternoon. As a result, the drivers had to be sure of warming their tyres up properly, in order to extract the best possible performance and guard against graining. In order to warm up the compound, the driver has to gradually put more heat and energy into the tyre during the out lap, so that the compound reacts with the surface to generate grip. Graining happens when the tyre simply skates across the asphalt rather than bonding with it, causing wave-like patterns of wear across the surface of the tread. Graining was seen for some drivers during Free Practice, but it remained within anticipated levels. Paul Hembery: “We’ve seen quite a big gap in terms of lap time between the two compounds today: between 1.4 seconds and 1.8 seconds depending on the team. These are exceptional circumstances because temperatures are a lot cooler than we would expect to see over the rest of the season, and with rain expected tomorrow, weather will obviously remain a big factor over the course of this weekend. There’s been some graining, but no more than we would expect under these circumstances. We’ll analyse all the data tonight but so far we would expect the teams to get about 20 laps out of a set of Soft tyres and approximately 25 laps out of a set of Mediums. Degradation on the Medium tyres is about half of what we are seeing on the Soft tyres: in terms of performance the medium tyre loses about 0.15 seconds per lap in race trim, whereas the Soft tyre loses about 0.3 seconds per lap. We’re looking at between two and three pit stops on Sunday from what we can see so far.” Pirelli fact of the day: The Pirelli factory in Yanzhou, China (one of two in the country) is the largest of the 22 factories in the entire group. Maximum capacity for car tyres in the plant is up to 10 million units per year. Subbed by AJN.