Different Types of Skid Marks a Car Can Makeby Matt Vietri
A skid mark is defined as a tire mark on asphalt surface produced by a tire that is not rotating. Skid marks are generally faded at the beginning and get heavier as they continue. The three main tire skid marks are acceleration scuffs, deceleration marks and yaw marks.
Yaw marks are what's left by a tire that is still rolling but is simultaneously sliding laterally. They are always curved and initiated by a steering input. If you're driving too fast into a corner you'll create a set of yaw marks. Yaw marks have distinct striations, stripes or streaks induced as the sidewall is dragged over the road. These marks are aligned in the direction of the spin, usually parallel to the car's axle.
If the drive tires are spinning faster than the vehicle speed, heavy burn marks will be left on the pavement at the inital point of acceleraton and the tire rib defintion may be visible in the center of the imprint.
Decleration 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 shoulder skid marks to be pronounced. Tire wear and inflation also play a factor in how pronounced the mark of the tire will be on the asphalt.
Imprint marks aren't exactly skid marks because they aren't caused when a tire skids on the asphalt--rather they are tire tracks. These occur when a car veers off the road or drives though water or mud and then the tires touch the road, leaving an imprint of the tire on the asphalt.
- Thorn Consulting Services: Speed from Skid Marks
- "Tire Imprint Evidence": Peter Macdonald,1993
- Harris Technical: Determining Vehicle Speeds by Skid Marks
- tires 2 image by Pontus Edenberg from Fotolia.com