Red Bull Still to Decide on Tyres for 2006

The Austrian-owned squad, currently using Michelin, are widely expected to switch to Bridgestone next season following the announcement that they will use Ferrari engines.

Horner, however, said a decision has not yet been made.

"We are very open on tyres," said Horner. "We will evaluate all the options and we will come to a conclusion towards the end of August, beginning of September, by then we will have all the facts.

"Tyres are the biggest influencing factor on the car, it is the most important decision we will take this year, bigger than the driver decision, bigger than the engine decision in many ways, and it is important that we get it right."

Horner denied their decision will be influenced by the deal with Ferrari, claiming Red Bull are totally independent.

"I can see how that conclusion can be drawn but that is not a given, because we are an independent team and we will make our own independent choice on tyres at the end of the day," he said.

Michelin-shod cars have won all but one of this year's races so far.