Pirelli motorsport boss Paul Hembery says better car balance and teams finding less pace than expected have contributed to Formula 1 reverting to more one-stop grands prix. The F1 tire manufacturer had intended two-to-three-stop races would be the norm in 2015.For the last two grands prix in Monaco and Canada...

Paul Hembery: "The variation in temperature we saw over the course of the weekend was quite remarkable, meaning that the drivers encountered different track conditions in every session. With such a wide spread of asphalt temperatures, you would ideally need more than just the two compounds stipulated in the regulations,...