Bridgestones Kobayashi on the 2010 tyre changes 05 Feb 2010
This weeks Valencia test was the first opportunity for the teams and drivers to sample Bridgestones 2010 specification Potenza F1 tyres. The new front tyres are 20mm narrower than 2009s - a move designed to redress the balance of the cars after grooves were removed for the start of last season. With refuelling now banned, the rear tyres also feature a new construction to cope with cars that will be heavier for longer during Grands Prix. Tetsuro Kobayashi, Bridgestone Motorsports technical manager, explains more and reviews testing progress
Q: Which specifications were brought to Valencia and why?
Tetsuro Kobayashi: We brought the Soft and Super Soft dry compound tyres to Valencia, along with our intermediate and wet weather specifications too. Valencia is a less severe track compared to some and although it has a slightly rough surface we are able to use our softer compounds here. One interesting factor at Valencia however is the front tyre graining caused by the lateral forces, which makes it a good track for us to evaluate the graining resistance of our front tyres. This is in contrast to the Jerez track, where teams will next test, which is much more severe, especially on the rear tyres. So we will be able to check our rear tyre performance more thoroughly next week.
Q: First test of the year with no fewer than seven teams: what was learnt from this test?
TK: First of all, we are pleased to have seen the good potential of the 2010 specifications, even though it's a little difficult to judge fully the true performance because of the special characteristics of the Valencia circuit. So far though, our tyre performance is in line with our expectations. We are expecting to learn more about rear tyre behaviour at the next consecutive Jerez tests where the rough tarmac and severe layout will provide a good testing opportunity for the Bridgestone rear tyres.
Q: The next two tests will be at Jerez. Which specifications will be seen there?
TK: The Medium compound will be supplied as the prime compound for both of the tests and the Hard and Soft compounds will be available during both week one and week two as option compounds.
Q: Why has Bridgestone only now developed the narrow front?
TK: The decision to change from grooved to slick tyres ahead of the 2009 season meant that the front tyres gained proportionately more contact surface area in comparison to the rear tyres. This in turn gave the fronts more grip than was ideally required. However, at the request of the teams, who had already designed their 2009 cars based on the previous sized fronts, we delayed the introduction of the narrow front until 2010.
Q: How much more narrow is the new front and did the teams have to do anything in particular to accommodate it?
TK: It is actually 20mm more narrow (including wheel width) than the 2009 specification (2010 front tyre size: 245/55 R13) and it enables the cars to be better balanced from front to rear. From the teams' perspectives, they should have taken these new fronts into consideration when designing their 2010 cars and they were asked in particular to consider designing the cars with more rear carrying load in order to get the best out of the tyres.
Q: What other changes has Bridgestone made to the tyres ahead of this season?
TK: Of course, being a new sized front, the front construction has been slightly modified but the other main change this year has been a change to the rear tyre construction in order to increase its durability. There has also been some modification of the tyre compounds in order to manage the expected longer stint lengths and to provide quicker warm up times in comparison to our 2009 compound range.
Q: How much work is involved from Bridgestone's perspective in designing, developing and manufacturing new tyre specifications?
TK: There is a great deal of effort required when designing and introducing new tyre specifications. Firstly, it is vital that the tyres are safe and of a high quality. They must also be capable of doing the job they have been designed for. Our tyre designers and engineers at our Technical Centre in Kodaira City, Tokyo, Japan, were extremely busy last year working on the prototypes and ensuring that the final specifications met the stringent quality and performance tests at our indoor testing facility. Only when tyres pass these tests on the rigs are they allowed to be run on the cars. It has to be said that the teams have also played an important part in this process as their simulation data is vital in ensuring that we are placing the tyres under the right amounts and types of loading. It is very much a collaborative process and we now look forward to seeing the tyres in action on the race tracks.
Q: Does the no refuelling rule and anticipated longer stint lengths place the tyres under added stresses?
TK: Certainly, with the cars being potentially 100kg heavier this year at the start of the races than last year, the longer stint lengths with greater amounts of fuel will place additional loads on the tyres but our 2010 casing should be much more durable in comparison to the 2009 casing: the strengthened rear construction in particular will help the cars accommodate this new rule. We will also keep monitoring and analysing the data very carefully at the coming winter tests and races because the downforce created by the 2010 cars will keep improving throughout the season. We have already noted that much higher downforces are being produced in comparison to last season.
Q: How will Bridgestone allocate the two types of dry tyre in 2010?
TK: Like 2009, Bridgestone intends to take two dry compounds which are a step allocation apart to most races: Hard and Soft or Medium and Super Soft for example. This will not be possible at some races however, such as Monaco, where it is important to have consecutive soft compounds to ensure maximum grip on the street circuit. The compound allocation will again be determined by Bridgestone, based on our experience of previous years and the data received from the teams.
Q: How many sets of tyres will drivers have available at race weekends?
TK: The number of sets of dry tyres to be made available in 2010 for each driver per race weekend has been reduced from 14 sets to 11 sets. These will consist of six sets of the prime tyre and five sets of the option tyre. Furthermore, we will provide four sets of intermediate tyre and three sets of wet tyre. This is welcome news from Bridgestone's perspective as we will have additional teams to supply and provide tyre fitting services to this year and we thank the FIA and teams for their co-operation in this regard.
Q: How will the tyres be visually distinguishable from each other this season?
TK: We will mark the softer of the two compounds available at each race weekend with green bands on the outer edges of the sidewalls. We tested many different alternatives and this location gave the best visibility, from the side and also a head-on view. We have used the colour green as it shows our support of the FIA's Make Cars Green campaign.