The rubber backing on the rugs is the culprit. Because vinyl and rubber don't mix, it creates a reaction and causes the vinyl to actually turn yellow. Also, other things can react and cause stains.

Rubber-backed bathmats or rugs can leave a yellowish stain on vinyl flooring. Chemical compounds, referred to as antioxidants, are formulated into rubber materials to extend the life of the rubber ...

Flooring experts agree that you should not use rubber-backed rugs on linoleum for just this reason. Hint: Your mats aren't the only thing that could stain this flooring.

More this week on vinyl floors being discolored by rubber-backed rugs. I really didn’t know how widespread the problem was when I first wrote about it because I don’t have vinyl flooring, but ...