Contactless tire inspection

Summary

Tire tread depth is one of the most important and most-ignored safety measurements on a vehicle. The traditional ways to check it — a tread-depth gauge pressed into each groove, a drive-over device that the tire physically rolls onto, or a stationary scanner that requires the car to stop and a technician to crouch — are slow, prone to operator error, or wear out quickly under repeated vehicle weight and road debris.

The clean alternative is to measure the tire optically, without contact, while the vehicle is in motion. But a side-mounted optical sensor sees the tire only for a fraction of a second as it passes, and tread depth measurement requires fine 3D detail — on the order of a millimeter — over a moving target in arbitrary lighting.

This pending application describes a low-profile drive-through inspection unit that projects structured infrared patterns at the side of each tire as the vehicle rolls past. Twin cameras — one per side of the lane — capture tens of frames per second of the projected pattern deforming across the tread, and a server reconstructs a 3D model from the triangulation to extract tread depth. A trigger (time-of-flight sensor or pressure cable) starts capture as the vehicle arrives, and a license-plate reader links each measurement to a specific vehicle. The system supports rapid fleet inspections at service bays and maintenance facilities — non-destructive, non-contact, no driver involvement.