Certain types of tires will stain our Diamond Flex Nitro Tiles and our other soft PVC garage tiles and garage rolls. Typically the types of tires that cause this staining are soft, performance tires. These tires have plasticizers in them that react with the vinyl. These substances are used to create a softer tire that will better grip the road when taking faster turns. Since the formulas for most tires are trade secrets, we truly don't know which tires will cause this issue. The only way to fix this issue is for you to put black tiles in the area where your car will be parked. If you do run into this issue, please contact one of our Customer Success team members via phone, email, or chat, and they will be able to assist you further.