Online Automotive Magazine
Camber on a Street Car: Handling Magic or Just a Waste of Tires?
January 18, 2007
Have you ever heard suggestions that a bit of negative camber can greatly improve the handling of your car? Maybe you're hesitant because you also heard that negative camber can destroy your tires on the street. I'll try to clear up this issue with some useful facts about camber and its effects on handling and tire wear.
To start out with, it is necessary to understand what camber is and why it is so important in suspension setup. Camber is, by definition, the angle of the tire relative to perpendicular from the point of view of the front of the car. Basically, it is the angle that the tire is leaned in our out. Positive camber is when the top of the wheel is leaned out from the car, and negative camber is when the top of the wheel is leaned in towards the car. Simple enough, right?
Now let's see why the angle of the wheel effects handling in a car. Most car suspensions are constructed in a way that causes camber to change as the suspension is compressed or as the car leans to one side or the other. In fact, it is very difficult and impractical to construct any suspension system where the camber does not change as the suspension compresses or rebounds.
With most car suspensions, as the car leans to the left in a right-hand turn, the camber on the outside wheel becomes more positive, and the camber on the inside wheel becomes more negative. Then naturally, we would want to make the outside wheel have negative camber and the inside wheel have positive camber. Thus, when the car leans in a turn, both wheels would level out. In other words, both wheels would have zero camber in the corner. This is exactly the condition necessary to have the most grip in a turn. If the camber is at zero degrees in the corner, then the tire is flat on the ground and the maximum amount of rubber is in contact with the road surface. The area of the tire in contact with the road at any time is appropriately called the contact patch. The tire can generate more gripping force if the contact patch is larger.
From the previous discussion, we know that, ideally, we want the inside tire in a turn to originally have positive camber and the outside tire to originally have negative camber. However, this creates a problem since we can't change the camber of the car if we first have to make a left-hand turn and then a right-hand turn. Of course, this problem is not encountered on an oval racetrack. If you are only making left turns on an oval racetrack, then the left side tires should have positive camber, and the right-side tires should have negative camber. The opposite is true if you are racing on an oval track with right turns. But we do have a problem on road courses with left and right turns.
On road courses, the best compromise is to have negative camber on both left and right side wheels. This is because the outside wheel in a corner takes much of the load of the car while you are driving through that corner. The weight shifts to the outside wheels taking weight off the inside wheels. Therefore, it's more important to have the right side wheels flat on the ground than the left side wheels.
As described, camber can indeed greatly improve the cornering ability of your car. However, from the above discussion, it is easy to see that camber can also wear out your tires relatively quickly. If you have negative camber on the car, then the inside of the tire will wear out quickly, and if you have positive camber on the tire, then the outside will wear out quickly. Thus, you should avoid using excessive camber on your car. For a street car, one to two degrees should be sufficient. With a small amount of camber, you can achieve a decent improvement in handling with only a small decrease in the life of the tire.