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Tire Impressions

Tire Impressions. Tire Impression Evidence. What is tire impression evidence? How is it involved in crime scenes? How is it collected? How is it analyzed?. What are tire impressions or tracks?. Tire Impressions are the tread design and dimensions of a tire.

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Tire Impressions

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  1. Tire Impressions

  2. Tire Impression Evidence • What is tire impression evidence? • How is it involved in crime scenes? • How is it collected? • How is it analyzed?

  3. What are tire impressions or tracks? • Tire Impressions are the tread design and dimensions of a tire. • Tire Tracks are the related dimensions of the 4+ wheels.

  4. Different Types of Tires: Original Equipment (OE) Tires • sold on new cars • thousands of cars have same brand and size Replacement Tires: • purchased to replace old, worn tires • usually different than OE tires

  5. Tire Impressions Design Elements: Grooves: around a tire Slots: across a tire Sipe: small grooves Tread Wear Indicator: raised bar under design; shows after wear

  6. Tire Impressions Noise Treatment: • If tire design was exactly repeated around the tire, noise would result. • Design repeated at different pitch lengths

  7. Tire Impressions Tire Track Evidence: Track width: measured from right center to left center Track width of front tires and rear tires are not always the same.

  8. Tire Impressions Tire Track Evidence: Wheelbase: measured from front center to back center

  9. Tire Impressions Tire Track Evidence: Turning Diameter: Diameter of a circle made when the wheels are fully turned.

  10. Tire Impressions Recovery of Tire Evidence: • Photos taken along with log of location. • Since tire tracks are variable along length (pitch), entire track should be photographed (examination quality) with overlapping photos. • Ruler included

  11. Tire Impressions Recovery of Tire Evidence: • Cast can be made of 3-D impressions • Long sections (3 feet) should be cast. • Use dental stone

  12. Tire Impressions Analysis of Tire Evidence: Class Characteristics can be used to eliminate a suspected tire or suggest a tire could have made the track. Class Characteristics: • Size • Tread design • Some wear marks

  13. Analysis of Tire Evidence: Class Characteristics can be used to eliminate a suspected tire or suggest a tire could have made the track. Known tires collected. Inked or 3D impressions can be made for comparison.

  14. Tire Impressions Analysis of Tire Evidence: • Similar to shoes, individual characteristics can be used to identify an exact tire. • Remember, individual characteristics change over time.

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