Kyle Petty, still mourning the death of his son, will not participate the next two weekends in The Winston or the Coca-Cola 600.
Petty pulled out of Saturday's all-star event and Steve Grissom will drive his car May 28 in the Coca-Cola 600, Petty Enterprises said Thursday.
Petty's 19-year-old son, Adam, was killed May 12 when he crashed during practice for the Busch 200 at New Hampshire International Speedway. His funeral was Monday.
The Petty family released a statement thanking fans for their support.
"We are truly grateful for the outpouring of support, prayers and love we have received over the past few days," the statement read.
"This is a very difficult time for all of us but we so appreciate the way our friends and fans from all over the world have expressed their love for Adam. We thank each and every one of you."
Crew chief Bobby Leslie said Kyle Petty was not up to racing.
Grissom drives for Petty Enterprises on NASCAR's Craftsman Truck Series and also is the test driver for Petty's Dodge developmental work in Winston Cup.
INDIANAPOLIS 500: Teammates Jimmy Vasser and Juan Montoya, the defending CART champion, led the day's practice with laps of 221.681 and 221.555, respectively.
Rain cut into practice time earlier this week, and the session began with a threat of more wet weather as well as strong winds that made the track treacherous.
But the rain was only intermittent and the action on the track was heavy, with 38 cars making laps.
Robby McGehee was next at 220.964, followed by Mark Dismore at 220.896, Scott Sharp at 219.921, Jimmy Kite at 219.810, Eddie Cheever at 219.670 and Buddy Lazier at 218.913.
The first of two days of time trials begins Saturday. The fastest cars will vie for the pole and the other top positions in the 33-car race-day field.
In the unique qualifying format, Sunday's time trials will fill the remainder of the lineup and allow some of the remaining entries an opportunity to bump out the slowest qualified cars.
WINSTON CUP: NASCAR's decision to add races could drive Mark Martin and other veteran drivers out of the sport sooner than expected. Many already have earned enough money and want to spend more time with their families.
Martin, 41, has been on the circuit since 1981.
"I don't plan to do this for another 10 years," he said. "I've put 26 years of full focus into (racing). If it was a 25-race schedule, I might plan to race another 10 to 15 years."
Martin still is pursuing his first title and is third in the points standings, just 33 behind leader Bobby Labonte.
Events were added at tracks near Chicago and in Kansas, putting next year's schedule at 36 races.
EUROPEAN GP: Mika Hakkinen isn't going anywhere but around the track. The two-time defending Formula One champion insists he has no plans to retire. The 31-year-old Finn has been the center of speculation that he will be replaced next season by Jacques Villeneuve. "The rumors are not true, I'm not going to retire," Hakkinen said at Nuerburgring, Germany.
WALTHER SENTENCED: Former driver David "Salt" Walther was sentenced to 180 days in jail for endangering his daughter's life by driving while under the influence of drugs.
Judge James Heath ordered the maximum jail sentence and a $500 fine. Walther will serve his sentence in the Warren County jail in Lebanon, Ohio.
Walther, 52, of Middletown, Ohio, was found guilty May 2 on a charge of child endangering. He was accused of being under the influence of drugs on March 19 when he returned his 4-year-old daughter to her mother in Springboro. Walther raced in the Indianapolis 500 seven times.