Which condition indicates a major issue with a vehicle's tire during inspection?

Excessive tread separation or bulging signifies a major issue with a vehicle's tire during inspection because it can lead to tire failure while driving, posing a significant safety risk. Tread separation occurs when the outer layer of the tire begins to detach from the inner layers, diminishing the tire's ability to grip the road and increasing the likelihood of a blowout. Similarly, bulging indicates that the tire structure has been compromised, possibly due to impact damage, which can also result in catastrophic failure while the vehicle is in motion.

In contrast, having no visible wear bars does not immediately indicate a significant issue, as it may simply suggest that the tires are not worn down to the level at which they need replacing, although it may require further evaluation. Matching tread depth across the axle is a desirable condition as it helps maintain balance and handling but, on its own, does not indicate any major issue. Normal air pressure is crucial for tire performance, but it alone does not point to a significant defect or safety concern with the tire’s condition. Thus, excessive tread separation or bulging is the clear indicator of a serious issue that warrants immediate attention during an inspection.