Mercedes drivers Lewis Hamilton and Nico Rosberg are favourites for the 2013 Monaco GP but Mark Webber, Kimi Raikkonen and Sebastian Vettel are contenders.
Kimi Raikkonen is weighing up two potential offers to remain in Formula 1 beyond 2013.
Toro Rosso's anticipated switch from Ferrari to Renault power for 2014 and beyond will be announced imminently, German magazine Sport Bild reports.
Mercedes executive director Toto Wolff says he trusts Pirelli to act fairly to all Formula 1 teams with the tyre changes set for the Canadian GP.
Lewis Hamilton will be reunited with Paddy Lowe sooner than expected after Mercedes announced that the former McLaren technical chief will join its Formula 1 team in June.
Changes to the Formula 1 tyres due to be introduced in June 2013 will be less dramatic than some have feared or hoped for, supplier Pirelli said on Monday.
Pirelli's planned changes to its controversial tyres for Canada and beyond are now under a dark cloud.