The objective of changing the performance window of the tires this year is to "open up more strategic options" for all the teams, Pirelli said at a press conference today in Milan.
"The 2013 season continues the philosophy adopted by Pirelli last year in evolving the original 2011 range of Formula 1 tires," Pirelli Motorsport Director Paul Hembery said at the event.
Mr. Hembery said despite Pirelli's best efforts last year — which helped produce seven winners in the season's first seven races — the F1 teams eventually came to grips with the tires and were able to make their chassis work in harmony with the tires. By the second half of the season races became more predictable and less competitive.
"Our 2013 range of tires mixes up the cards once more to help overtaking and ensure two to three pit stops per race," he said.
The tires developed for 2013 feature softer compounds, more flexible sidewall structures and more robust shoulders, Pirelli said.
The softer compounds— the PZero Orange "hard" compound tire this year is roughly equivalent to last year's medium compound — allow the tires to reach peak operating temperature faster, which should yield lap times about a half seconds faster than last year, Pirelli said.
Reaching peak operating temperatures more quickly leads to the tire's peak performance window being extended, Pirelli said. Traction is also improved, especially on the exit of corners and in combined traction areas, from braking to acceleration and vice versa.
The construction changes mean slightly heavier tires. A set of tires this year weighs roughly 4.4 pounds more than last year, but Pirelli said the FIA took this into consideration when setting the car's minimum weight limit.
The development included thousands of computer simulations carried out by Pirelli's engineers throughout the 2012 season and backed up by laboratory tests on the compounds together with data collected during grands prix and roughly 4,000 miles of testing.
Pirelli supplies each F1 team with 11 sets of tires per car for each race weekend —six sets of the harder and five of the softer compound. Tires are assigned randomly by the FIA. In total Pirelli takes about 1,800 tires to each race.
Pirelli has produced a video that explains the new tires and their performance characteristics.