Italian Grand Prix, Mugello: Bridgestone debrief with Masao Azuma

Yamaha Factory Racing’s Jorge Lorenzo rode an inspired race at Mugello last Sunday, winning his third race in a row at the Italian circuit ahead of Repsol Honda’s Dani Pedrosa and Monster Yamaha Tech3’s Cal Crutchlow.

Excellent conditions greeted riders at this year’s Italian Grand Prix with the dry Mugello tarmac reaching a peak of 44°C during both Saturday and Sunday afternoon, ensuring the teams had plenty of relevant set-up data for the twenty-three lap race.

Bridgestone slick compounds available: Front: Soft & Medium. Rear: Soft, Medium & Hard (Asymmetric)
Bridgestone wet tyre compounds available: Hard (Main), Soft (Alternative)

Q&A with Masao Azuma – Chief Engineer, Bridgestone Motorsport Tyre Development Department

All of the rear slicks brought to Mugello this year featured Bridgestone’s heat-resistant construction. Can you explain why these tyres were supplied and did they do the job last weekend?
“After the new 1000cc MotoGP machines were introduced last year, Bridgestone reviewed its tyre severity rating for every circuit on the calendar. These ratings are based on the number of right and left-handed corners, the type of asphalt used and many other factors that contribute. Using this rating system, Mugello has always been one of the more severe circuits in MotoGP for tyres, but the increase in loads generated by these heavier, more powerful motorcycles increased the stress endured by tyres at this circuit to a point where the heat-resistant construction was needed. As a result, we decided that for this year, the best decision for the safety of the riders was to supply all our rear slicks at Mugello in our heat-resistant construction.

“Also, as we are supplying rear slicks to the CRT riders this year that are one step softer than the works riders, it means for the first time our soft rubber compound was used on the right shoulder of a rear slick option at Mugello. The use of this soft compound on the right shoulder means we decided to use heat-resistant construction for the CRT-specific slicks for safety reasons as well, and the results were as we expected; quite positive.

“Some riders do notice a slight difference in grip from the edge of the tyre with this heat-resistant construction compared to our regular slicks, however, the performance these tyres offer is still extremely high. Proof of this point was that new qualifying and race lap records were set at Mugello last weekend using the heat-resistant rear slicks.”

With some circuits on the calendar being harsher on tyres than others, why doesn’t Bridgestone need to create heat-resistant front slicks at the more severe circuits?
“The rear tyres on a motorcycle are subjected to much more stress than the front tyres. The front tyres have to deal with cornering and braking forces, however the rear tyres also have to cope with transferring the power to the ground when the bike accelerates and it is this that creates very high temperatures. Front tyre temperature increases when braking, but the total braking time for one lap is usually much less than the time spent accelerating.

“The range of temperatures a front tyre is subjected to during a race is a lot less than the rear tyre. Therefore, even at those circuits that are the most severe on front tyres such as Aragon and Sepang, our regular construction front slicks are more than able to cope with the stresses placed upon them by the MotoGP machines.”

The 2013 Italian Grand Prix was held earlier in the year than usual, did this have much bearing on the tyre allocation for this year?
“Reviewing the historical data we could see that generally track temperatures at Mugello are quite high, but this year not only was the race held earlier, mainland Europe has experienced unusually cool weather this spring. We considered these factors when deciding on our tyre allocation for the Italian Grand Prix, particularly for the front slicks. In fact, we waited until the Wednesday before the race weekend to lock in our front tyre allocation, as we wanted the most accurate predictions of what the weather would bring.

“If the weather conditions for the weekend would have been much warmer, than we considered offering a selection of front slicks one step harder than originally intended. However, in the end our original front tyre allocation worked well as track temperatures on Friday morning were very cold, and so we had to make sure the riders had front tyres that warmed up as quickly as possible on a track that was quite greasy due to the recent rain. Basically, we kept our original tyre allocation for Mugello, though we were prepared to change it just before the race weekend if required.”

Source: Bridgestone Motorsport