Goodyear Tire Chief Executive Rich Kramer said on Thursday the company had clarified its policy to make clear that its employees can wear apparel expressing support for law enforcement after it faced a boycott call from US President Donald Trump.

Goodyear tyres are seen on the presidential limo known as "The Beast" as US President Donald Trump arrives for a nearby re-election campaign event after landing aboard Air Force One at Wilkes-Barre Scranton International Airport in Avoca, Pennsylvania.

The Republican president, who is seeking a second term in office, told reporters on Wednesday he would swap out the Goodyear tyres on his presidential limousine if there were an alternative.

Goodyear on Thursday said it had a longstanding policy of asking employees to refrain from working place expressions of support for any political candidates.

Trump accused the Ohio-based company of “playing politics” by forbidding workers from donning the “Make America Great Again” caps favoured by his supporters.

“Don’t buy GOODYEAR TIRES - They announced a BAN ON MAGA HATS,” Trump wrote on Twitter on Wednesday, referring to his slogan “Make America Great Again” often emblazoned on baseball caps.

Trump said it was “disgraceful” that the company would prevent employees from wearing attire supporting the ‘Blue Lives Matter’ movement that supports law enforcement while allowing support for other causes.

Goodyear said a widely circulated image created by a plant employee that triggered the controversy was not created or distributed by the company’s corporate group.

The image spelt out appropriate and inappropriate displays, with ‘Black Lives Matter’ and ‘Lesbian, Gay, Bisexual, Transgender Pride’ deemed acceptable, while ‘Blue Lives Matter’ and ‘MAGA Attire’ were not.

Kramer said Goodyear “strongly supports” law enforcement, noting it has supplied tyres to police and fire vehicles for more than 100 years. “That relationship is foundational to our company,” Kramer wrote employees Thursday. “Goodyear has always supported both law enforcement and equal justice.”

Shares in Goodyear fell as much as six percent on Wednesday after Trump’s tweet, but pared some losses to close down 2.4 percent. Goodyear shares fell 0.4 percent on Thursday to US$9.46.

The White House did not comment on Goodyear’s new statement, but White House economic adviser Larry Kudlow earlier defended the boycott call, saying Goodyear should change its workplace policy to allow political speech.

- Reuters