The key to Chevrolet’s domination of the Nextel Cup tour this season, Toyota’s Lee White said, might be a secret tire war between Goodyear and Michelin. With NASCAR barring teams from testing on Goodyears, Nextel Cup teams have turned to rival tire makers, including Michelin, through its B.F. Goodrich division. That has become quite the hot potato in behind-the-scenes talks between NASCAR executives and Goodyear officials.