The big news in tyres is that Pirelli will make three types of tyre compounds available but at least two must be used during the race, but teams can use three different compounds.

How the 2016 Formula 1 tyre rules will work - F1 news -

Some are of the opinion that during 2015, Mercedes was strongest on medium and hard tyres, where as the Ferrari's were able to make the softer tyres last longer.