Goodyear, which had nearly $15 billion in revenue last year, said a widely circulated image that triggered the controversy was not created or distributed by the company's corporate group.
The image spelled 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.
"To be clear on our longstanding corporate policy, Goodyear has zero tolerance for any form of harassment or discrimination," the company said in a statement.
To enforce that policy, Goodyear said, it asks employees to avoid "workplace expressions in support of political campaigning for any candidate or political party as well as similar forms of advocacy that fall outside the scope of racial justice and equality issues."