1. Forensic Tire Tread and Tire Track Evidence

2. Tire tracks are important in forensic investigations and are usually found in road accident scenes or in the access and escape routes of other crime scenes.

3. Features to analyze:
Tread pattern
Width & depth of the tread pattern
Wear pattern or defects

5. Tire databases are available help investigators determine the brand and model of the tire, which can be used to determine the type of vehicle that made the tracks.

6. Tire impressions reflect the tread and dimension features of individual tires on a vehicle

8. Contact Patch – portion of tire touching the ground

9. Stress Cycle – Under the load of a vehicle, rotating tire goes through stress

10. Tread Wear Indicator is a raised rubber bar 1/16 of an inch above base of grooves of tire

11. Noise treatment – tire industry created tire designs that vary the size of the spacing. This reduces or controls noise when driving.

12. Could two vehicles leave the same tire marks?
Write out your answer in the space provided
Explain why or why not. Be specific and provide examples!

13. Tire Track Evidence Tire track evidence consists of: Tire track width
Wheelbase dimensions
Turning diameter
Relative positions of turning tracks

14. Track Width (Stance) – measurement made from one center of one wheel to opposite center of wheel

15. Wheelbase – measurement of center of hubs of front wheels to center of hubs of rear wheel
Normally these measurements are not present at crime scenes

16. Tire Positions in a Turn
When vehicle moves in straight path, only the rear tire tracks are available
When a vehicle turns, rear and front tires track separately
Important to understand and document at crime scenes

17. Front wheels turning produce unreliable measurements
Rear wheels accurately record turns