Tires are put under a tremendous amount of stress on a daily basis. They're expected to maintain their shape, offer extended tread life, and prove capable on a variety of road surfaces. Tires are also expected to offer excellent agility and maneuverability in combination with a vehicle's suspension. Tire performance is measured in a number of ways, including a tire's ability to grip the road through a variety of driving maneuvers. One measurement of both the safety and the performance capability of tires is that of the slip angle.
What is Slip Angle?
When breaking down the details of slip angle, it can become quite convoluted and difficult to understand. On a basic level, slip angle is calculated with an equation based on several performance measurements and specifications of a particular tire.
In reality, slip angle isn't incredibly difficult to understand. Slip angle will vary based on many tire design variables, including type of tire construction and compound materials used in that tire. It includes the width of the tread, the shoulder materials, tread patterns, sidewall ratio and available footprint (otherwise called the contact patch) which remains through a turn. Variances in vehicle speed and road surface will also potentially affect the tire's slip angle.
Consider a simplified definition of slip angle. The slip angle is calculated based on the difference between the direction tires are meant to drive a vehicle and the actual path that the vehicle travels. When a tire corners, the contact patch will eventually begin to slide slightly toward the outside of the turn. This is due to the pliable nature of tire rubber and is unavoidable. But don't worry, just because a tire slips a small amount doesn't mean that it's unsafe. Just keep in mind that the slip angle will increase at higher speeds.
Slip Angle Differences in Tire Design
Let's compare them to racing tires. Racing tires are manufactured to be driven at high speeds by driving professionals, and a large slip angle, which will vary from track to track, allows these drivers to maintain high speeds. In order to provide a safer tire, and a tire that is capable of maneuvering when needed, passenger tires are constructed to offer a little more bite than that of a racing tire.
The slip angle allows for the racing technique popularly known as drifting. As suspected, drifting, which is a wider slip angle or greater ability to drift, wouldn't benefit the daily driver who's attempting to stay within a lane of traffic or quickly avoid an obstacle. Ideally, the slip angle of most vehicles traveling at legal speeds should be approximately 5 - 10 degrees. Tire manufacturers test the slip angle under various conditions on test vehicles. Third-party publications also test slip angle to offer unbiased reviews and advice to consumers. These tests can help you decide which tires are right for the type of driving you do and the conditions that you might face.
When is Slip Angle an Important Factor?
Most often, the slip angle isn't something that drivers need to be incredibly concerned about unless you need to corner, or turn, often. For drivers who rely on a steady dose of cornering daily, a tire that is capable, sturdy, and doesn't allow for too much slip is a necessity. This is especially true for individuals who live in a mountainous area and commonly drive winding and narrow roads calling for additional tire safety concerns.