Formula One hopefuls Stefan GP have been forced to cancel a planned test in Portugal later this week because they lack a tyre deal.
The Serbian team do not have a 2010 entry but are still keen to race this year given newcomers Campos and US F1 might fail to make the first Grand Prix of the season in Bahrain on March 14.
"We cannot do the test at the moment and we are still trying to find a solution," boss Zoran Stefanovic told autosport.com on Monday. "We have no tyres and will not test on tyres that are not suitable for the car to go testing at full speed."
Stefanovic said last week he was close to signing former world champion Jacques Villeneuve as a driver although the Canadian has slightly cooled the speculation.