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Published byRebecca Freeman Modified over 9 years ago
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Tire Impressions
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Tire Impression Evidence What is tire impression evidence? How is it involved in crime scenes? How is it collected? How is it analyzed?
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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. Tire Impressions
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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 Tire Impressions
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Design Elements: Grooves: around a tire Sipe: small grooves Slots: across a tire Tread Wear Indicator: raised bar under design; shows after wear Tire Impressions
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Noise Treatment: If tire design was exactly repeated around the tire, noise would result. Design repeated at different pitch lengths Tire Impressions
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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. Tire Impressions
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Tire Track Evidence: Wheelbase: measured from front center to back center Tire Impressions
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Tire Track Evidence: Turning Diameter: Diameter of a circle made when the wheels are fully turned. Tire Impressions
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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 Tire Impressions
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Recovery of Tire Evidence: Cast can be made of 3-D impressions Long sections (3 feet) should be cast. Use dental stone Tire Impressions
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Analysis of Tire Evidence: Class Characteristics can be used to eliminate a suspected tire or suggest a tire could have made the track. Size Tread design Tire Impressions Some wear marks Class Characteristics:
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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. Tire Impressions
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Analysis of Tire Evidence: Similar to shoes, individual characteristics can be used to identify an exact tire. Remember, individual characteristics change over time. Tire Impressions
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