Physical Examination Of Tyre Marks

Tyre marks are present in many hit and run cases or rash driving cases.

1. Physical Examination Of Tyre Marks Presented By :- Nishant P. Hole Volunteer Of AFRS

2. CONTENTS Introduction Types Characteristics Identification Examination Forensic Significance References

3. INTRODUCTION Tire marks are produced when a tire slides across a paved surface, leaving dark rubber particles on the pavement. Similar to the way an eraser leaves particles on a piece of paper. These are marks on road resulting from friction caused by vehicle tyres locked in position of brakes.

4. TYPES OF TYRE MARKS 1] Yaw Marks :- Yaw marks made by a tire that is rotating and sliding slideways parallel to that wheel’s axle ; also referred to as slide-slip or critical-speed scuff marks. If a vehicle yaws, then the velocity of directions deviates from its heading .

5. 2] Tire Scrub Marks :- A skid mark caused by the vehicle being redirected as a result of a collision ; mark generally look like irregularity shaped smears and are characteristics of the point of impact.

6. 3] Skid Marks :- Skid marks caused by tires on roads occurs when a vehicle wheel stops the rolling and a slides or spins on the surface of road. The Skid marks can be analysed by to find the maximum and the minimum vehicle speed prior to an impact or an incident. The Skidding can also occurs on the black ice or the diesel deposits on the road and it may not leave a mark at all.

7. Skid marks are classified into following types : 1] Acceleration Marks :- If the drive tires are spinning faster than the vehicle speed, heavy burn marks will be remains on pavement at the initial view of accelerator. The tire rib maybe visible in the centre of an imprint.

8. 2] Deceleration Marks :- Deceleration marks occur when tires are spinning slower than the vehicle because of braking or downshifting. When a vehicle brakes a greater portion of the vehicles weight is transmitted to the outer edges of the front tires. This causes parallel skid marks.

9. 3] Imprint Marks :- It occurs when a car veers off the road or drives within water or mud and then the tires touch a road, leaving an imprint of the tire on the asphalt. Imprint marks aren’t exactly skid marks because they aren’t caused when tire skids on the asphalt rather they are tire tracks.

10. CHARACTERISTICS The class characteristics include general patterns and size. An individual characteristics include daily wear and tear, accidental cuts as well as holes. Depending upon the surface and circumstances of the track, characteristics may be reproduced in the tracks left by the tire.

11. IDENTIFICATION 1] Width of Tyre :- The tyre width is a distance between two edges of the tyre and the size varies for scooters , cars and buses , etc. 2] Circumstances of Tyre :- It is an important for determining the size as well as the type of the tyre . 3] Tread Pattern :- Tyres are different from one to another and hence it help to identify the make of the tyre .

12. EXAMANINATION Tyre tread impression is to be photographed at the crime scene whether or not a casting must be made. If the object containing the impression cannot be taken to the laboratory for casting or further analysis then the three dimensional tyre impression must be made. More times there are difficulty in examine or making a better cast and if it is not possible then photographic technique must used. In many cases, impression may extend to several feet resulting in very bulky casts. According to the negative cast being made, it was compared with negative since likes only can be subjected comparison.

13. FORENSIC SIGNIFICANCE Tyre marks and tyre have acquired great importance in criminal investigations and their evaluation help in:- Identification the vehicles which are involved in hit and run cases. solving cases involving kidnapping. Indicating mode of arrival of the suspect and his departure from the crime. Finding out the hideouts of the criminals by trailing.

14. REFRENCES https://www.merityre.co.uk/tyres/introduction-to-tyre-markings . https://study.com/academy/lesson/tire-marks-forensic-examination-methods-purpose.html . https://www.forensicsciencesimplified.org/fwtt/how.html .