Pirelli have been doing a bit of tweaking during the off-season. Tyres now have more colour and the intermediate tyre markings have turned green. The hard tyre will be much faster than it was last season because all of the compounds have closed up together a bit more. So there is now about 0.8 seconds between each compound, rather than about 1.5 seconds.
http://www.autosport.com/news/report.php/id/97170
http://www.autosport.com/news/report.php/id/97169