Achieving optimum camber is all about improving tire grip. Driving on icy or muddy roads can quickly teach you the importance of grip. When your tires lose it, you'll have less control of the vehicle. Even in dry conditions, the camber or angle of your tires has a lot to do with how well they grip the road. The more surface area between your tire and the road, the better the grip and the more stability you'll have.
Ideally, the tread surface of each tire will be flat relative to the ground. But most streets aren't completely level -- they're sloped a little. Because of this, slightly positive -- we're talking maybe half a degree -- rather than zero camber will give you optimum surface contact and grip [source: Brand]. That is, as long as you're driving straight ahead. Making a fast turn will change things.
To understand how turns change the game, imagine a car with zero camber on a perfectly level road. When it makes a sharp left, the car -- tires included -- will tilt to the right. At this point, the wheels' camber is no longer zero relative to the ground. The tilted tires are now sharing less surface area with the road and consequently have less grip.
When performance drivers want maximum cornering control, they put negative camber on all wheels. This way, during a turn, the entire tread surfaces of the outside tires -- which carry more weight than the inside ones -- achieving optimum grip. For those who want to increase street cornering performance, experts recommend a half a degree of negative camber [source: Alexander]. But since cornering performance is especially important for a race car, each of its wheels has a steeper angle of negative camber.
Notice that with negative camber, the inside wheels still lose surface area during a turn. But, as we said, ideal handling includes all tires being flat relative to the ground. On the street or on road courses with left and right turns, this isn't possible, and negative camber ends up being the best compromise.
On oval NASCAR tracks, however, where race cars make only left turns, things are different. With left turns, NASCAR cars use negative camber for the right wheels, which will always be on the outside of a turn. For the left wheels, they use positive camber, because those wheels will always be on the inside of a turn. With this ideal cornering combination, NASCAR race cars can have optimal grip and stability during a turn and thus maximum corning speeds.
Determining the best angle can depend on a few different factors, and getting the right balance can be difficult. For example, if the track is banked -- sloped inward at the corners -- then you probably don't need much camber. But too much of it has disadvantages. For instance, with excessive camber, you have less grip on straightaway driving -- meaning slightly worse acceleration and braking when a car isn't in a turn. Camber also wears on the lower edges of a vehicle's tires when driving straight, which can lead to blowouts [source: Briggs].
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