By Alan Baldwin
BIRMINGHAM, England (Reuters) - Formula One should be wary of forcing drivers to make more pitstops as part of future efforts to make races more exciting, according to tyre supplier Pirelli's motor racing head Mario Isola.
The idea of having two mandatory pitstops in a grand prix, rather than just one at present, has been around for some years and remains under discussion as the sport plans a major rules revamp after 2020.
"There was a lot of talk about imposing two stops by regulation," Isola told Reuters in an interview at the Autosport International show.
"I'm not sure that is the right solution because you have the risk of all the cars stopping on the same lap," added the Italian.
The suggestion was discussed last year, but nothing was changed for 2019, as the sport looked at how to encourage more varied team strategies amid concern about the number of one stop races.
Isola said removing the obligation for the top 10 to start the race on tyres used in the second phase of qualifying was also still 'on the table'.
Pirelli have simplified their colour-coded range of tyres for 2019 from seven to three (soft, medium and hard), making it easier for the casual fan to know what is being used.
Isola said the tyres should also be more consistent, allowing drivers to push slightly harder.
"We want to be a bit more conservative because if we have one stop races anyway, at this point it's much better that we give drivers a bit more consistent tyres and they can push more and maybe we have a better show on track," he added.
He warned, however, that making tyres less susceptible to over-heating remained a problem.
"We made some improvement on the product itself, we’ve different compounds in order to reduce the over-heating. But the over-heating is not avoidable when you follow another car and you lose a lot of downforce," he said.
Formula One has already announced that the tyres will change from 13-inch (33.02 cm) wheel rims to 18-inch ones in 2021, when tyre warmers -- used to raise temperatures before the race for better grip and performance -- will be banned.
Isola said the combined changes posed a major challenge for Pirelli, who last November won a tender to remain as sole supplier until the end of the 2023 season.
The bigger tyres will have to be safe at temperatures ranging from 20 degrees Celsius when leaving the garage to 120 during the race, with a corresponding increase in pressure.
The 2021 technical regulations, aiming to facilitate overtaking by allowing cars to follow more closely, have yet to be finalised, however, and time is pressing.
"We already started to design the new tyres because we cannot wait. The deadline was already in the past," said Isola.
"What we can do is adapt the tyres, the design, to the new rules when they are available. But we need to know at least 80-90 percent of the expected performance of the cars as soon as possible... without that information it is really a challenge.
"We have two years in front of us before using the 18 inch tyres so it’s important that we use this time in a good way. We cannot lose time but I believe we can do something good if we have the right process."
The Italian said Pirelli would devote the first part of 2019 to developing next year's tyres and then switch their full focus to 2021.
"We don’t want to stop the development of the 2019 product because there is something more we can do and we know that," he said. "But for sure, the second half of 2019 will be dedicated to 18 inch tyres.
"I would say six months for 2020 and then we switch to 18 inches and dedicate 100 percent of the people to the new size and new challenge."
(Reporting by Alan Baldwin, editing by Christian Radnedge)