What are the signs of a defective windshield installation?

Choosing air or water leaks as a sign of a defective windshield installation is accurate because these leaks directly indicate that the windshield may not be sealed properly against the vehicle's frame. A well-installed windshield should create a watertight and airtight barrier. If there are gaps or inadequate sealing, it can lead to water intrusion during rain or washing, and air leaks can compromise the integrity of the cabin environment, possibly leading to noise and comfort issues.

In contrast, improperly installed wipers, unusual tire wear, and malfunctioning headlights do not directly relate to the installation integrity of the windshield. While these issues can indicate problems with other components of the vehicle, they do not reflect the quality or correctness of how a windshield has been installed. By focusing on air and water leaks, one can more accurately assess potential failures in the windshield seal, making it a key indicator of installation quality.