Riggs, the polesitter, was dominating the race when the right front tire on his Dodge went flat on lap 141. Kvapil raced around the slowing Riggs on the backstretch and drove his Chevrolet to the victory.

Just three laps earlier, Riggs' Ultra Motorsports teammate Ted Musgrave dropped out of second place into the pits. He too had a flat right front on his Dodge.

"We were the winner by default ... I'll take it," Kvapil said. "No question the No. 1 and No. 2 Dodges had us. We struggled early, but we kept digging."

Kvapil, who led twice for 14 laps, finished a half-second ahead of Rick Crawford's Ford, the only non-Chevrolet in the top eight. Kvapil averaged 112.020 mph in the race slowed by seven caution periods.

Jack Sprague maintained his slim lead in the season points title with three races left by finishing third.

Riggs, who led 128 of 147 laps, dropped all the way to 13th. Musgrave was 10th. Both have five wins this season.

Riggs started on the front row with Musgrave, and some of the few laps he didn't lead before the flat tire came on two pit stops. The first came when two trucks stayed on the track and the other when Kvapil beat him out of the pit during the sixth caution.

Kvapil had the lead on the restart of lap 107, but a lap later Riggs forced himself back in front after getting on Kvapil's bumper. The rookie got loose and Riggs charged under him and back in front, where he stayed until his flat.

When Terry Cook and David Starr stayed out on the track during the fifth of seven cautions, Riggs was third on the restart on lap 87. By time they got back to the start/finish line, Riggs was back in front.

Bryan Reffner, who won at Texas last fall, was knocked out of the race after being caught up in a six-truck crash on the third lap. It was a chain reaction after Carlos Contreras apparently lost control on an oily spot in the third turn.