Which of the following conditions warrants taking a tire out of service?

A tire should be taken out of service when there is any tread or sidewall separation because this condition indicates a significant safety risk. Tread separation can lead to tire blowouts, loss of vehicle control, and accidents, especially when transporting hazardous materials. The integrity of the tire is critical for maintaining traction, stability, and proper handling of the vehicle.

Tire inspections are vital for safety; thus, any indications of separation must prompt immediate action to replace the tire. Other conditions, such as normal wear or slight discoloration, do not necessarily compromise the tire's structural integrity or safety to the same extent, making them less critical when determining whether a tire should remain in service.