Istanbul: Formula One`s long wait for a 2011 tyre deal will continue into next week after 11th hour talks with Michelin at the Turkish Grand Prix on Sunday.
Japanese company Bridgestone is quitting the sport in November and the teams, eager to get on with designing their 2011 cars, had originally hoped a deal would be signed with a new partner by the end of last month.
The negotiations, seemingly narrowed down to a choice between French company Michelin and Italy`s Pirelli, remained inconclusive three races later.
"There was a lot of general discussion, it`s going to take a little while longer," Mercedes team boss Ross Brawn told Reuters after leaving a 90-minute meeting at the McLaren motorhome in the Istanbul Park paddock.
Williams chief executive Adam Parr added: "We are still in the process of making the final decision, I`m afraid.
"It`s taking a bit longer than we`d like but it`s going very well and we`ve got proposals from both of them," he said.
"Today was nothing new, just running through the ideas. Just to make sure we full understand everything. I think it will take a few more days but we are getting close."
Pirelli, who supplied tyres for the first ever F1 championship race in 1950 but have been absent since the early 1990s, were seen as favourites for the deal before the weekend. Michelin quit Formula One at the end of 2006.
"I think Pirelli will be really positive for F1," Red Bull team boss Christian Horner had said earlier in the week.
"They are a quality company, they are a good brand to have in F1 and I think it is good news for F1. It is also really a good quantity of tyres they are looking at supplying and we are looking forward to working with them."
However Michelin motorsport head Nick Shorrock flew to Istanbul to meet teams on Sunday.
"The objective of this morning was simply to make sure that the teams had fully understood the details of our offer," he told reporters in the Renault motorhome, adding that no improved terms were put forward.
"The teams listened, they asked questions and we have tried to clarify as much as possible any doubts that they had."
Brawn said earlier that whoever won the contract would be expected to meet precise technical specifications put forward by the teams.
"The teams have together produced a technical specification of the tyre we want," he explained. "That means we can continue with the development of our cars. Our cars are being designed around the current tyres because we have no other information.
"The teams are also working together...to try and restrict (for next season) some of the variables that we have on the cars that may be influenced by the tyres," said the Briton.
"Things like weight distribution and so on may be something which we will seek to limit for the first year while we get settled in with a new tyre supplier."
Testing is banned as part of cost-saving measures but the Mercedes team chief said some tests would have to be scheduled this year for familiarisation purposes.
"I think late summer and early winter there will be some tests organised with the new tyre supplier," said Brawn. "But we must try and accommodate that within the teams we have. We can`t afford to go out and start rebuilding test teams again."