Tongues were wagging in the Barcelona paddock on Thursday when some drivers hit the Spanish circuit wearing odd-looking Pirelli tyres.
Some of the tyres, whose compounds are normally visibly differentiated with coloured branding, featured significantly different markings.

The big rumour was that, now just two weeks before the start of the season in Australia, teams had requested the blank tyres in order to hide their test programmes from their rivals.

According to France’s Auto Plus, motor sport director Paul Hembery cleared up the matter by explaining that the blank tyres were in fact “prototypes”.

They had been manufactured not at Pirelli’s usual F1 factory in Turkey, but elsewhere, in the event that a natural disaster forced the tyre supplier to change its plans at the last minute.

Hembery also answered the criticism that, after Pirelli’s initial 2011 tyres spiced up the racing early last year, the new generation might not be aggressive enough.

“We need data from the races to judge that,” he insisted. “It’s far too early.”

He also confirmed that Pirelli is close to announcing the identity of its 2010-specification test car, and a new test driver.

It is believed former Force India driver Adrian Sutil is a candidate.

It is now clear that next year’s formula one tyres will be identical to the ones used in the feeder series GP2.

We reported last month that, as Nick Heidfeld began testing Pirelli’s F1 prototypes at Mugello, also running the tyres for the Italian marque was a GP2 car driven by Briton Ben Hanley.

Pirelli’s track programme continued last week at Paul Ricard, where this time alongside Heidfeld’s 2009 Toyota was Giorgio Pantano in the GP2 Dallara.

“We were using the same tyres as Heidfeld with the 2009 Toyota,” confirmed GP2 technical director Didier Perrin, according to Germany’s Auto Bild.

“This is good news because it means you can use the same tyres in both series, which is important for Pirelli and GP2.

“For the GP2 drivers, it means them racing on the same tyres as in formula one, which would be very useful for their futures,” Frenchman Perrin added.

Pirelli will soon name its formula one test driver.

Reports have linked Mercedes reserve driver Nick Heidfeld with the role of helping the Italian marque to prepare for the 2011 season.

It is believed Pirelli will conduct six tests before all the teams try the tyres for the first time in Abu Dhabi in mid November.

A spokesman for Pirelli’s F1 programme said this pre-Abu Dhabi testing, reportedly with a 2009 Toyota car, will not begin until “about September”.

“At the moment, we have produced the first scale models of the tyres, at 50 per cent size, for the purposes of wind tunnel testing,” he said.

“The four compounds are currently being worked upon, with the prototypes scheduled to come out next month.

“There was a test that took place at Paul Ricard in France recently, but that was for GP2 tyres.  There, we completed more than 120 laps with no problems.”

As for a driver for the F1 tests, the spokesman said an announcement can be expected “either next week or the week after”.

He said “two permanent test drivers” will be appointed, “one for F1 and one for GP2″.

“Details of the F1 car we will be testing with” will also be provided, the Pirelli spokesman added.