Australian Grand Prix debrief with Tohru Ubukata
Bridgestone slick compounds available:
Front: Soft, Medium.
Rear: Hard, Extra Hard (both asymmetric)
Bridgestone wet compounds available:
Phillip Island usually provides mixed
weather during the grand prix weekend and this season was no different with rain on Friday that delayed running by two hours and eventually resulted in a wet but drying session, showers that interrupted practice and qualifying on Saturday but then fine weather and the highest temperature of the weekend for Sunday's race. As expected, the temperature was cold but the new asymmetric rear tyre developed by Bridgestone for Phillip Island, with an extra soft compound right shoulder, performed well. Casey Stoner was the runaway winner ahead of Jorge Lorenzo and Valentino Rossi, having emerged ahead of his race-long battle with Nicky Hayden.
Q&A with Tohru Ubukata - Manager, Bridgestone Motorcycle Tyre Development Department
How did the cold conditions affect tyre performance over the weekend?
"Especially on Friday and Saturday morning the track temperature was low, but no lower than we expected so this did not come as a surprise because we believe our spec choice has a wide enough operating range to cover such cold temperatures. The combination of rain, the cold and the high winds made the conditions very challenging for the riders, but we can see from the laptimes that tyre performance was good in all conditions. The left side of the rears were a harder compound to cope with the demands of the fast lefts but the right side of the rear slicks was softer to aid warm-up performance and grip in the cold. Even though tyre temperature was lower than last year, it was still within their wide operating range. It was very tricky in the wet because the ambient temperature was even lower when it rained, but this is why we chose the soft compound wets. Overall, and taking into account rider feedback most of which was positive, I am happy with the performance of our tyres this weekend."
What was the biggest challenge for the tyres over the weekend?
"Phillip Island is an unusual circuit because the difference between the ambient temperature and the tyre temperature, especially in the left shoulder of the rear tyres, is greater than at any other circuit. The ambient and track temperatures were generally low, but the temperature the left shoulders reach are the highest of the season so balancing this was tricky. We use asymmetric rear slicks to manage this balance between warm-up performance in the right with durability in the left of the tyres, but generally wet tyres do not need to be asymmetric because the peak tyre temperature is much lower so the difference between the temperature in each shoulder is much smaller than in the slicks. Because of the nature of this circuit and the fast left-handers though the left side of the wets reached a high temperature and this increased their wear rate and led to some riders feeling that the rear was moving a lot when the track started drying. Slick tyre performance was good as proved by the laptimes, especially Casey's, but I can say that the biggest challenge of the weekend was for the wet tyres in the drying conditions."
How successful were the new rear slicks that used the extra soft compound in the right side?
"I am very happy with the performance of our new asymmetric slicks. We developed them for Phillip Island specifically for the cold conditions that we expected, and in these conditions they provided improved warm-up performance and good grip. I am pleased that we also received great feedback from the riders who all believe they are an improvement on the rear tyres we brought here last year. We will adopt this extra soft compound into the asymmetric rear slicks we will use in Estoril and Valencia because of the cold conditions we expect at each circuit."