Pirelli has surprised the F1 world by revealing an aggressive selection of tyre compounds for the start of the 2013 season.The biggest of them is the choice for the Melbourne opener, as Pirelli opts to supply to teams the Supersoft and Medium compounds.F1 correspondent Livio Oricchio commented: "These (supersoft) tyres offer great grip, but have a short life."F1 SHAKE UP The 2013 season will be the first for which Pirelli has nominated its softest compound for Australia. In 2012, Pirelli supplied Soft and Medium compounds to teams in Australia.Pirelli said: "The full step in the compound choice should ensure a performance gap between the cars that allows strategy to come into play."There is also an all-new selection for April's Bahrain GP - Hard and Soft compounds, compared to the 2012 selection of Soft and Medium.Pirelli's motorsport director Paul Hembery said the idea was to shake up F1 teams' knowledge of Pirelli's tyres. "We found that by about the middle of the 2012 season the teams had adjusted almost a little too well to our compounds."So, in close consultation with the FIA, we have made the task more difficult."