AUSTIN, Texas - Tyremaker Pirelli has warned it would "take a very conservative approach" to 2014 unless its mandate was clarified by Formula 1.F1's official supplier has been the subject of intense criticism about the quality of its tyres in 2014 but boss Paul Hembery insists many have forgotten that the company was tasked by Bernie Ecclestone to spice up the racing by producing aggressive tyres that degraded quickly.'WE WANT CLEAR GUIDANCE'That mandate, however, was never enshrined in the rules. Hembery argues many of the sport's leading figures have forgotten that: "We just want to know what we should do. We want clear guidance."Hembery admitted Pirelli's US-race tyre selection - hard and medium compounds - was "on the conservative side" and warned that, if Pirelli's role was not clarified, the sport should prepare for more "one-stop races" in 2014.