How are straight skid marks measured?

How are straight skid marks measured?

• A. Measure only the first 2 meters
• B. Use average tire width
• C. Pick out each tire and measure the entire distance; if unable to pick out each tire, deduct the wheelbase
• D. Count number of skid marks

Answer: (C)

Measuring straight skid marks focuses on how far the tires actually slid during braking. Each tire leaves its own skid path, and the length of that mark reflects the distance that particular tire traveled while stopping. The most accurate method is to identify every tire’s skid and measure its entire length along its path, so you capture the true braking distance for each tire. If the marks are hard to distinguish and you can’t separate each tire’s track, you can estimate by subtracting the vehicle’s wheelbase—the distance between the front and rear axles—from the total skid distance. This helps approximate the distance the vehicle traveled during braking when individual tire marks can’t be clearly separated. Measuring only the first portion, using tire width, or simply counting marks does not provide the actual stopping distance needed for speed estimation.

Measuring straight skid marks focuses on how far the tires actually slid during braking. Each tire leaves its own skid path, and the length of that mark reflects the distance that particular tire traveled while stopping. The most accurate method is to identify every tire’s skid and measure its entire length along its path, so you capture the true braking distance for each tire. If the marks are hard to distinguish and you can’t separate each tire’s track, you can estimate by subtracting the vehicle’s wheelbase—the distance between the front and rear axles—from the total skid distance. This helps approximate the distance the vehicle traveled during braking when individual tire marks can’t be clearly separated. Measuring only the first portion, using tire width, or simply counting marks does not provide the actual stopping distance needed for speed estimation.