Which of the following is true about tires that have been repaired by plugging?

The statement that tires that have been repaired by plugging pass as long as the plug is in the tread is true because tire plugs are considered an acceptable method of repairing punctures that occur in the tread area, where the tire maintains its structural integrity. When properly installed, a tire plug can effectively seal the puncture and restore the tire's air retention and performance.

It is important to note, however, that this is specific to punctures in the tread area only, and plugs should not be used for sidewall damage or when the tire has other underlying issues. While repairs should always comply with safety standards set by relevant authorities, a properly done plug in the tread does meet the criteria for passing inspection.

In practice, options emphasizing that tire repairs are always unsafe, are dependent on the repair being conducted by a licensed individual, or that tires must be replaced entirely do not reflect the standards of tire repair as accepted in safety inspections.