Camber is the inward or outward tilt of the tire/wheel assembly. This angle is measured from a true vertical line, i.e. perpendicular to the ground. A tire/wheel assembly that is tilted outward at the top is considered to have Positive camber. While a tire/wheel assembly tilted inward at the top, displays Negative camber. For a zero setting, the tire/wheel assembly is in the exact vertical position or perpendicular to the ground. To rephrase, if the top of the tire/wheel assembly is tilted inward towards the engine, it has a negative camber. If the top of the tire/wheel assembly is tilted outward from the engine, the camber is positive.
This is Negative Camber
This is Zero Camber
This is Positive Camber
Effects of Positive Camber
Slight positive camber results in a dynamic loading that allows the tire to run relatively flat against the road surface. Positive camber also directs the weight and shock load of the vehicle on the larger inner wheel bearing and inboard portion of the spindle rather than the outboard bearing. Positive camber in moderation results in longer bearing life, less likely sudden load failure, and as a side benefit, easier steering. Excessive positive camber wears the outside of the tire and can cause wear to suspension parts such as wheel bearings and spindles.
Effects of Negative Camber
Variations in negative camber can be used to improve the handling of a vehicle. A setting of 1/2° negative on both sides will improve cornering without affecting tire life greatly. This negative setting compensates for the slight positive camber change of the outside tire due to vehicle roll, thereby allowing a flatter tire contact patch during cornering. Excessive negative camber wears the inside of the tire and similar to positive camber, it can cause wear and stress on suspension parts.
Road Crown and Camber
A crowned road means that the outside/right hand side of the lane is lower than the left side of the lane. This improves the drainage of the road but adversely affects vehicle handling. Road crown must be compensated for in alignment settings because a vehicle driving on a crowned road leans to the right, causing some weight transfer to the right, and the camber changes slightly more positive. This combination creates a pull or drift to the right. Most alignment technicians adjust the vehicle with a slightly more positive camber, usually 1/4°, on the left to compensate for the road crown. This slightly more positive camber will not cause a noticeable pull when driving on a flat road. However, if camber is unequal from side to side with a difference greater than 1/2°, the vehicle will pull to the side with the most positive camber. If the specifications allow, 0° to ±.5° is usually best for tire life and vehicle handling.
Causes of Camber Changes
Always consult a ride height specification book prior to beginning alignment. If out of specification, attempt to correct. Changes in ride height from factory specifications affect camber. As a vehicle ages, the suspension has a tendency to sag. The weight of the vehicle can cause springs to weaken. Springs can also be damaged by excessive vehicle loading or abuse. Another factor to consider is sagging of center support or crossmember. Modifications to the vehicle such as raising or lowering the suspension or changing the total weight of the vehicle can also affect camber.
