Types of Tires for Cars

A car's tires are one of its most important parts. They represent the place where the car meets the road. Tires account for a good portion of a vehicle's safety, performance and efficiency. Knowing the different types of tires available and choosing those that best suit your needs is important to good driving.

Major Categories

Most tires included on new vehicles or sold as standard replacements fall into one of several main categories. These categories are based on the intended use of the tires, and designate tires made from different materials and using different tread patterns for specific purposes. Performance tires, sometimes sold as "high performance" use softer rubber for better traction on dry pavement. The softer composition means a shorter lifespan, but these tires are best for high speed maneuvering and fast acceleration. All-season tires come on most new cars. They are meant to be driven in a variety of conditions, and represent a compromise between the other types of tires. Mud and snow (M&S) tires are meant for use in snowy or icy conditions and use wide, deep tread to keep traction even in extreme conditions.

Tire Sizes Explained

It is, of course, important to choose the proper size tires for the wheel they will be mounted on as well as the vehicle itself. Using tires that are even slightly larger or smaller than required by the manufacturer can lead to inaccurate speedometer readings and can put undue stress on a car's suspension and drivetrain. To aid in choosing the right size tires, all tires have their size rating printed on their sidewall. This code begins with a "P" which stands for passenger car. Next comes a three-digit number that is the size of the tire measured in millimeters. A slash mark separates that number from the next number, which is the tires proportion (expressed as a ratio of its height to its width). The letter "R" is usually next, designating that the tire is a radial style tire. Finally, a two-digit number stands for the diameter of the wheel that the tire is meant to be mounted to, measured in inches.

Tire Ratings

A tire's quality can be determined by looking at another series of letters and numbers printed on the sidewall. These characters measure temperature, traction and tread wear. The temperature rating is a latter from A (tires designed to withstand very high or very low temperatures) to C (those that might not operate as well under both extremes. Traction ratings are also designated by letters, with AA indicating a tire with excellent traction. A, B and C ratings are applied to tires with decreasing traction properties. Lastly, tread wear is measures with a number, usually in the 300 to 500 range. These ratings are percentages that indicate how long the tire's tread can be expected to last compared to an arbitrary control tire. For example, a tire with a 300 tread rating can be expected to last three times as long as the control tire, while one with a 600 rating will likely last twice as long.

Speed and Load Ratings

Each tire is also rated for speed and weight of the load it can carry. Load ratings use a series of charts and alphabetical designations to compare tires to one another, though the amount of weight a tire can actually carry is determined by the vehicle's manufacturer. Tire load ratings are useful only in comparing one tire to another.

On the other hand, speed ratings are very specific and set by the maker of the tire. A series of letters, printed on the tire itself, correspond to a list of maximum speeds at which that [particular tire is thought to be safe and reliable. An M rating is the lowest and represents an 81 mile per hour maximum speed. At the other end of the scale is the Y rating, which corresponds to a top speed of 186 mph.

Vehicle Manufacturer Ratings

The familiar stickers that are often applied to the doors, door frames, or under the hood of all care are where the automaker indicates the recommended load rating and tire pressure that should be observed by drivers. These stickers also contain the required tire size. The number listed as GVWR is the gross vehicle weight rating, and is the most weight that should ever be carried in passengers and cargo. Tire pressure is measured in pounds per square inch (psi). Tires should be checked often and air added or released as necessary. Whatever type of tire is being used, proper inflation means that the car can achieve its maximum performance and efficiency. Underinflated tires also represent a danger in terms of increased stopping distance and poor handling.

References

• Tire Rack
• Tire Types

Resources

• How to buy car tires