Asymmetric Tyres Allow MotoGP Tyres “Good Overlap of Performance” in Assen
MotoGP’s Dutch TT Grand Prix this weekend – the 80th meeting held at the circuit – yielded a significant success for Bridgestone, the series’ sole tyre supplier. Throughout the weekend, the tyre manufacturer states, riders were lapping competitively on each specification, and the race provided a direct comparison between the extra edge grip of the softer rear slick option and the additional traction of the harder option. The balance between the medium and the hard asymmetric rear tyre options was illustrated by the podium: Jorge Lorenzo took his fourth win of the season using the hard option, with Dani Pedrosa and Casey Stoner coming second and third respectively using the softer rear tyre. While the circuit was modified in the Ruskenhoek corner, shortening it by 13 metres, the new lap record set by Dani Pedrosa was two seconds faster. The track temperature was high, reaching 47 degrees Celsius, and the weather was fine throughout the weekend maximising the riders’ dry running time.
Tohru Ubukata, manager of Bridgestone Motorcycle Tyre Development Department commented on the mix of rear tyre choices: “Last year we brought soft and medium tyres to Assen, and almost all riders used the medium compound for its extra durability on the right side. This year we brought asymmetric tyres to Assen, and also went one compound step harder as part of our process of continual development and improvement. This means that this year the riders could choose the medium or the hard compound rears for added durability in the right shoulder, whilst the soft compound rubber in the left shoulders retained warm-up performance and edge grip on the left side.
“Our objective for tyre development in the single tyre era has always been to increase their temperature operating range; that is the range of conditions and track temperatures in which each specification can perform well. Indeed, we were doing this even before our appointment as the single supplier. Our achievements in this area mean that we now have a good overlap of performance between our different tyre compounds, and as we saw in particular this weekend both the medium and the hard asymmetric rear tyres offered similar levels of performance.
“Tyre choice for the race therefore came down to rider preference and machine setup. Jorge was able to extract maximum performance from the hard rear and benefit from its increased durability, whereas Dani and Casey were able to use the softer option and benefit from its increased edge grip and initial performance in the early stages of the race. Some riders and bikes use the tyres harder than others and generate higher tyre temperatures so we recommend either one of our tyre options based upon attaining the optimum tyre temperature for each rider, machine and tyre package.”
While the rear tyre specification was split amongst the field, all the riders chose to use the medium option front tyre: “Firstly, the front tyre options we brought to Assen were softer than the rear: we selected the soft and medium fronts whereas the rears were our medium and hard compounds. If the temperature was cooler, some riders may have used the soft front for its extra edge grip, but as it was with a track temperature in the race of 47 degrees Celsius, the harder front tyre provided greater braking stability and more consistent front-end feeling for the riders.”
Ubukata suggested the modification to the circuit had had little effect on the tyres: “The change to the circuit layout didn’t impact upon tyre shoulder performance as although corner speed was higher through Ruskenhoek as a result, loads were not excessive and tyre temperatures were still well within operating range. I can say though that the affect it did have was under braking into the right hander after, Stekkenwal. Carrying more speed through Ruskenhoek meant heavier braking into Stekkenwal which created more load on the centre of the front tyre, which was another contributing factor to all riders using the harder front for the race.”