Today's Michigan 500 Indy-car race was postponed for one week after two accidents during practice yesterday cast doubts on new radial tires provided for the $600,000 event.

The change was announced after a meeting between CART officials, track management and representatives of the Goodyear Tire & Rubber Co. racing division. The race was to be telecast live by NBC, which will instead show last year's race.

The meeting was called after a morning crash involving Bobby Rahal, who set a track record Friday in his March-Cosworth and won the pole in qualifying. Rahal eclipsed Johnny Rutherford's year-old mark of 215.189 mph with a speed of 215.202.

Rahal, who will retain the pole, was not injured in the crash that occurred when two tires on his car "lost air pressure due to an undetermined cause," a Goodyear spokesman said. Rahal's car was extensively damaged. Rahal had crashed his primary car in practice Friday, forcing him to move to his spare.

Of today's crash, Goodyear engineers said "there was evidence the two tires may have been punctured but additional time is required for a more thorough analysis," the spokesman said. Roberto Guerrero also spun during the morning session, apparently because of tire problems.

Officials at the two-mile oval speedway said bias ply tires will be used July 28. The Michigan 500 was to have been the first race on a super speedway to use radial tires . . .

Geoff Bodine, without the mysterious fuel additive that disqualified him from the pole, slowed to 150.238 mph to land the No. 22 slot in qualifying for today's Pocono 500 stock car race in Long Pond, Pa.

Bodine registered a 152.460 in Friday's opening qualifying round but was forced to requalify when NASCAR officials discovered the fuel infraction.

Darrell Waltrip, who had a second-best time of 152.220, was awarded his fifth pole of the season.

Meanwhile, Bill Venturini was in serious but stable condition after his stock car crashed into a wall during an ARCA 150-mile race at Pocono.

A part in the suspension of Venturini's Chevrolet Monte Carlo apparently broke shortly after the race began, and the car slammed hard into the wall during the first turn. Track physicians said he possibly had a concussion and fractures of the upper left arm and upper right leg. Bobby Schacht won the race by two seconds over Bosco Lowe . . .

Curtis Markham of Richmond won his sixth Winston Series late-model stock-car event this year at the Old Dominion Speedway in Manassass. Markham, driving a Camaro, crossed the finish line of the 35-lap race approximately two seconds ahead of Roger Austin of Nokesville, Va., who drove a Camaro. Joe Cudmore of Greenbelt, also in a Camaro, was third.