Target Chip Ganassi managing director Mike Hull says IndyCar made the call on its own and that his team will test the new car later this year.
Four-time series champ Dario Franchitti was scheduled to run at the 1.5-mile oval Wednesday and Thursday. He and Wheldon were close friends.
Franchitti's wife, actress Ashley Judd, wrote on Twitter: "I appreciate IndyCar canceling my husband's test at Las Vegas track. The new car needs development – but not now, and never again there."