Eric Maycroft was suspended by NASCAR and subsequently released by Michael Waltrip Racing after he was found to have violated the sanctioning body's substance abuse policy.
Maycroft was the front tire changer for Martin Truex Jr.
In a NASCAR release announcing the suspension Tuesday afternoon, NASCAR said that Maycroft's violation was found on August 16.
Shortly thereafter, Michael Waltrip Racing issued a statement saying that Maycroft was no longer with the team. As per NASCAR policy, the type of substance was not released.
"Michael Waltrip Racing fully supports NASCAR's substance abuse polices and those who complete the Road to Recovery program," the statement said. "MWR's zero tolerance policy has resulted in the immediate termination of the employee."
Truex is currently 12th in the points standings and in the final Wild Card spot thanks to his win at Sonoma.