Introduction:
Tire Impression is 2D or 3D marks that reflects the tread design and dimensional features of a tire.
Tire Track is the Relative dimension between two or more tires of a vehicle
Principle Behind Tire Track:
The basic theory behind Tire Track analysis is the examination by investigators of imprints or impressions left by any vehicle.
The type of Evidence left behind depends largely on the type of travelled surface. For eg. a tire will leave impression on loose sand but on a hard surface like concrete it will leave an imprint.
Tire treads and Sidewall components:
In this section, we learn about the different Elements of a tire for the better understanding of tire track or impression or imprints.
This help us to better understanding of a crime scene.
Tire Treads and Sidewall components can also help us to make a correlation with the manufacturer of the tire
Tire treads are ridges and grooves that channel water away from the wheel and provide traction for the vehicle.
i. Tread patterns can be measured and used to identify the type of tire, and sometimes even the make and model of the vehicle that left the mark
Types of Characters:
Class Characteristics:
Class Characteristics are basically a number of similar characteristics that are shared by more than a number of objects.
Eg. Two tires of some brand, model and Size will have identical tread design and dimensions but may have slight differences due to imperfections in moulds used during manufacturing.
Individual Characteristics:
Indivisible Characters are those which are unique to any particular object and doesn’t shared by similar characters with any other of its kind.
Eg. These could be from damage such as cut, crack or a temporary alteration like a stone or twig stuck in tread.
Types of tire marks:
Skids marks
*Brakes suddenly
*Locked wheels
*Calculate velocity from skid marks
Yaw marks
*Produced when a vehicle travels in a curved path faster than the vehicle can handle and skids sideways
*Tires and road surface melt from extreme temps
*Often smoke occurs
Tire scrubs
*Damaged or overloaded tires after impact
*Usually curved
*Determine area of impact
Importance of tire marks:
*Tire evidence can be used to link a suspect to a crime scene and also to help the crime scene investigators reconstruct the crime.
*Like other impressions, tire marks may leave patent, latent, and plastic markings.
i. Latent impressions occur when a car travels over a liquid such as paint, blood, or tar.
ii. Latent tracks can be deposited from the oil used to soften tires.
iii. Plastic impressions can be made when a vehicle drives on mud, sand, or snow.
*To help identify a vehicle, investigators measure track widths, wheelbase lengths, and turning diameter and check them against a vehicle database.
*Tire marks can also give clues to speed and direction of the vehicle.
*Investigators will use information provided by evidence to try to reconstruct an accident.
