Looks like the B/Y 400 tire issues still aren't solved yet.

http://thescore.ibj.com/blogshell.asp?p=983

Last year, the race was yellow flagged every nine laps to avoid tire blowouts, in what many called the worst NASCAR race of the year. NASCAR officials told IBJ the problem is not completely solved. Recent tire tests showed the Goodyear tires might last 15 to 25 laps depending on the weather.

Twenty five laps is optimistic. One NASCAR insider said “one good rain” shortly before the race could wash all the rubber out of the racing groove and cause big problems with the race yet again. There is one more tire test scheduled before this year’s Brickyard 400, where Goodyear will continue to wrestle with the rubber compound mix.