 Complete the following phrase:  In 1992, following the exit of Pirelli, Goodyear became the sole tire supplier for Formula One for four years until Bridgestone entered the sport in 1997, creating a tire war between the two manufacturers. Goodyear would leave the sport following the 1998 season, leaving Bridgestone as the sole tire provider for the next two seasons until Michelin entered the sport in 2001, creating another tire war between the two manufacturers that lasted until 2006. The tire wars during this period has been cited as a reason for six-car start at the 