The third round of the MotoGP World Championship takes the teams to the Estoril circuit for the Portuguese Grand Prix on May 1.
This year the date of the race has been brought forward from the October slot it has inhabited for the last two years and the MotoGP teams and riders will be hoping for better weather after last year was hit heavily by rain.
The Grand Prix marks the first use this season of Bridgestone’s asymmetric rear slick MotoGP tires, which have been selected because of the imbalanced demands of the circuit.
There are nine right-handed corners and only four lefts, and generally the right-handers are faster and generate higher loads, resulting in markedly higher tire temperatures in the right shoulders of the MotoGP tires, especially the rears.
Estoril MotoGP is a very varied circuit, mixing a top speed of over 325km/h along the main straight with heavy braking for the first corner, the very slow first gear chicane of turns nine and ten, and the long and fast final corner, Parabólica.
Owing to this variation in corner speeds and types, asymmetric rear slicks are essential in providing the MotoGP riders with consistent levels of grip throughout a lap. The left shoulder of the rear tires is subject to much lower loads and temperature so needs to be softer to offer good warm-up performance and grip from cold, whereas the right shoulder experiences high temperatures, especially as riders open the throttle out of Parabólica and onto the main straight, so is a harder compound rubber.
The softer option rear slicks use Bridgestone’s extra soft compound in the left shoulder and medium compound rubber in the right, and the harder option rears feature soft compound rubber in the left shoulder and the hard compound in the right.
The temperature is expected to be higher than experienced in Estoril’s October MotoGP date, but not significantly so as to make a difference to tire selection. Exactly the same compound specifications have been chosen by Bridgestone as last year.
Hiroshi Yamada (Manager, Bridgestone Motorsport Department) says: “It’s been four weeks since the Spanish GP because of the postponement of the Japanese MotoGP from last weekend so everyone will be keen to go racing again.
“The disastrous events in Japan have not affected our MotoGP tire supply though so there will be no problems in Portugal. This year the Portuguese GP has been moved from October but this change doesn’t make a significant difference from a tyre perspective, other than hopefully meaning less chance of rain!
“The conditions last year at Estoril were very difficult for the riders as the race was the first dry session of the whole weekend, almost exactly the inverse of the conditions we saw last time out at Jerez. Jorge has won this Grand Prix for the last three years so will be a strong force again this season, but after the action-packed last race in Spain there will be many riders looking to make amends and get more points under their belts.
“Our tire compounds in Portugal are exactly the same as we selected for the race last year when feedback of our extra soft compound was very positive, so I am looking forward to another exciting race followed by a valuable post-race test on Monday.”
Hirohide Hamashima (Director, Bridgestone Motorsport Tyre Development) says: “Estoril features one of the highest top speeds of the season although has nearly the slowest average speed and its main challenge comes from the varied nature of the corners and the imbalance between right- and left-handers.
“The nature of the track changes from one corner to the next, and the tyres also have to contend with a surface change during the lap after partial resurfacing work conducted in 2006. The combination of fast and slow corners including the fast, long final corner and the very slow chicane demand the use of asymmetric rear slick tyres to balance the tyre temperature in each shoulder and provide consistent grip throughout the lap.
“It’s a slippery circuit so this demands softer compounds to generate grip and good warm-up performance in the left side of the tyres, but the fast and long right-hand corners necessitate harder compounds in the right shoulder of the rear slicks to cope with the increased temperature. The heavy braking points, especially into turn one, require a strong front tire so we have to achieve a balance with our tyre selection.”
Bridgestone slick compounds available for Estoril MotoGP: Front: Soft, Medium. Rear (asymmetric): Medium, Hard