Major change needed to fix Williams F1 tyre problems, says Bottas

Throughout this F1 season, Williams has struggled to get the various tyre compounds into the right operating window.

The team secured third in the constructors' championship for the second consecutive year last time out in Brazil and is now fully focused on its 2016 preparations.

When asked if Williams was close to getting to bottom of its tyre problems, Bottas admitted: "Not really.

"We have some tools to try to cool the tyres and create temperature, but we are at the limit at the moment.

"We can't do any more with the brake ducts or anything to make the tyres even more cool.

"We know it's not enough but at least for this season there's nothing more we can do."

When asked if fundamental change was required next year to cure the problems, Bottas said: "I think so, yes.

"The team has definitely been looking into that. Hopefully next year we can make all the compounds work well."

Williams performance chief Rob Smedley said he was pleased with the way the team has reacted to its tyre problems but believes it must become "proactive" if it is to catch rivals Mercedes and Ferrari.

"Fundamentally you know how to use the tyre - you know what ranges to put the tyre into - but there are very clear nuances from track to track," he said.

"The very best people, they understand all the nuances from track to track and they're able to be proactive. They're able to come to the track with a plan.

"I think we have good contingencies and we work well in a reactive kind of way.

"We still don't have yet all of our scientific bases covered in order that we can be entirely proactive and simulated and we can come here knowing exactly what we're going to do.

"We cope very well reacting to situations but we need to go a step further than that and be proactive."