A federal court in New York last week denied plaintiffs' motion for class certification in a case alleging that the run-flat tires on defendant BMW's MINI Cooper S were defective. See Oscar v. BMW of North America LLC, No. 1:09-cv-00011-RJH (S.D.N.Y. 6/7/11).

Oscar purchased a new 2006 MINI Cooper S from BMW-MINI of Manhattan, an authorized MINI dealership, but prior to purchasing the MINI did not do any sort of research. Nor did he take the car for a test drive. The car came with run-flat tires (RFTs), an innovation that allows drivers to drive to the nearest service station even after the tire was flat. As of December 2, 2009, a period of about three years, Oscar had had five flat tires. Plaintiff alleges that his troubles stemmed from the fact that his car was equipped with RFTs rather than with standard radial tires. He considered the number of flat tires he experienced to be evidence of a widespread defect.

Plaintiff proposed a nationwide class (or a New York class) of all consumers who purchased or leased new 2005, 2006, 2007, 2008, and 2009 MINI vehicles equipped with Run-Flat Extended Mobility Technology tires manufactured by Goodyear and sold or leased in the United States whose Tires have gone flat and been replaced.

On the first prerequisite of Rule 23(a), the court offered an interesting discussion arising from the fact that most of plaintiff's evidence of numerosity did not correlate directly to his class definition: data that may have included other vehicles, or non-RFT tires, or makers other than Goodyear. But the opinion noted that courts have relied upon "back-of-the-envelope calculations in finding numerosity satisfied." Conservative assumptions leading to a likelihood of numerosity have at times sufficed. This case fell "right on the border between appropriate inference and inappropriate speculation." Accordingly, numerosity was satisfied for the proposed national class but not the New York class.