What is the standard for vehicle deviation?
2 Answers
The standard for determining whether a vehicle deviates is as follows: a new vehicle on a straight and level road (with a national standard-defined right tilt angle of less than 2 degrees), with the steering wheel centered, traveling at 80 km/h for 8 seconds. If the vehicle's deviation distance is less than one lane width (approximately 3.75m on highways), it is considered normal. Definition of deviation: Deviation refers to the phenomenon where a vehicle moves to the right or left when driving straight on a flat road with the steering wheel centered. Causes of deviation: Road inclination or unevenness. On a perfectly flat road, the vehicle will drive straight with the steering wheel centered. However, most roads in China are slightly inclined to both sides (to facilitate drainage). When the road inclination exceeds 1 degree, the vehicle may exhibit slight deviation, which is a normal response to the road surface. Uneven tire pressure can also cause deviation when there is a difference in pressure between the left and right wheels. Uneven vehicle load can lead to increased resistance on the heavier side, causing the vehicle to deviate toward that side. Mechanical issues may also cause deviation. If road conditions and tire pressure are ruled out, potential vehicle faults should be considered, such as issues with the braking system, suspension system (shock absorbers, springs, lower control arms), or steering wheel alignment.
Last time I drove a long distance, I felt the steering wheel always pulling to the left, which was really annoying. Car drift generally refers to the vehicle involuntarily veering to one side while driving. The standard check is usually to see if the car severely deviates from its original trajectory a few seconds after releasing the steering wheel. If the deviation angle exceeds 5 to 10 degrees, it needs attention. Common causes include uneven tire pressure (especially in winter when tires deflate too quickly), wear and tear in the suspension system causing left-right imbalance, or wheel hub deformation affecting the steering angle. I recommend starting with simple tests: first, check if the air pressure in all four tires is consistent; then find a flat road to test drive, driving slowly and releasing your hands to observe the degree of deviation. If it keeps veering, you’ll need to check the chassis or go to a professional shop for a four-wheel alignment. Don’t underestimate it—over time, it can lead to uneven tire wear, affect braking performance and fuel consumption, and increase driving risks. In short, the standard lies in the degree and persistence of deviation, so address it early if detected.
