Tire

A tire (U.S. spelling) or tyre (UK spelling) is a roughly toroidal piece of material placed on the circumference of a wheel, either for the purpose of cushioning or to protect the wheel from wear and tear.

Automobile tires

Automobile tires have numerous rating systems.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

The size of a tire is measured with a single code, in the form AAA/BBRCC for radial tires. This code is often a source of confusion, as its format is an obscure mix of inches, millimeters, and percentages.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

In this form, AAA is the width of the tire, measured in millimeters. 200 is a common figure, but the range can be quite wide. The 2000 Honda Insight uses 165 mm wide tires, while the rear tires of the 2000 Dodge Viper fit 335 mm tires.

Related Topics:
2000 - Honda Insight - Dodge Viper

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

BB is the "profile", i.e. the height of the sidewall (the distance from the edge of the wheel to the edge of the tire), measured as a percentage of AAA, the tire width. A 200/50 tire would have a 100 mm high sidewall. If the number BB is missing (e.g. 145/R12) then the height is 80% of the width.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

CC is the diameter of the wheel the tire is designed to fit on in inches. With of all three of these numbers you can calculate the total diameter of the tire.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

New automotive tires now also have ratings for traction, treadwear, and temperature resistance (collectively known as UTQG ratings); as well as speed and load ratings. Some tread designs are unidirectional and the tire has a rotation direction. Tire rotation moves tires between the different wheels of the vehicle as front and back axles carry different loads and thus the tires wear differently.

Related Topics:
Tire rotation - Axle

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Tire tread gauges are small rulers designed to be inserted into tire treads to measure the remaining tread depth. Local legislation may specify minimum tread depths, typically between 1/8" (3.2 mm) and 1/32" (0.8 mm). Wearbars may be designed into the tire tread to indicate when it is time to replace the tire. Essentially, part of the tire tread is shallower than the rest and will show when the tire is worn down to that level.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

There is currently an attempt to reinforce the tire with nanomaterial. This is likely to increase the tire life, but may turn out to be a bad idea if the worn out part of nanocarbon deposited on the roads is washed off and end up in the food chain.

Related Topics:
Nanomaterial - Food chain

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Types of automobile tires

• Performance tires
• Performance tires tend to be designed for use at higher speeds. They often have a softer rubber compound for improved traction, especially on high speed cornering.
• Performance tires are often called summer tires, because they sacrifice wet weather handling, by having shallower water channels, and tire life from softer rubber compounds, for dry weather performance. The ultimate variant of perfomance tires has no tread pattern at all and is called slick tire.
• Winter tires
• Winter tires are designed to remain pliable in subzero temperatures. They often have fine grooves and siping in the tread patterns that are designed to bite into the ice and snow on the road. Winter tires are usually removed for storage in the spring, because the rubber compound becomes too soft in warm weather resulting in a reduced tire life.
• Many winter tires are designed to be studded for additional traction on icy roads.
• All-season tires
• Most automobile tires are all season tires. These tires are an attempt to satisfy the needs of most road conditions, they have the deeper water channels that are found in winter tires, but often have harder rubber compound for greater tire life in warm weather.
• All-season tires attempt to strike a balance between performance, wet weather and comfort.
• All-terrain tires
• All-terrain tires are typically used on SUVs and light trucks. These tires often have stiffer sidewalls for greater resistance against puncture when traveling off-road, the tread pattern offers wider spacing than all-season tires to evacuate mud from the tread.
• Within the all-terrain category, many of the tires available are designed primarily for on-road use, particularly all-terrain tires that are originally sold with the vehicle.
• Mud tires
• Mud terrain tires are characterized by large, chunky tread patterns designed to bite into muddy surfaces and provide grip. The large open design also allows mud to clear more quickly from between the lugs.
• Mud terrain tires also tend to be wider than other tires, to spread the weight of the vehicle over a greater contact patch to prevent the vehicle from sinking too deep into the mud.
• Depending on the composition and tread pattern, many mud terrain tires are not well suited to on-road use. They can be noisy at highway speeds, and due to the open tread design, they have less of a contact area with the road, limiting traction. The large lugs on mud tires tend to tear and chip on roads, because they are made from hard rubber compounds that do not bend easily.