About Rims and Tires · 07/25/2006
This article is based on the Wikipedia articles "Wheel," believed to be by JDG, Patrick, Dbachmann, Natalinasmpf, Jimbowley, et al, and "Tire", believed to be by G4sxe, SteveBaker, Pgk, Morven, Dmccreary, et al, here modified and published by Artful Media LLC. Modifications © 2006 Artful Media LLC. Permission is granted to copy, distribute, and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2, or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
A wheel is a circular object that, together with an axle, allows low friction in motion by rolling. Common examples are found in transport applications, such as cars, motorcycles, bicycles, and trains.
According to most authorities, the wheel-and-axle combination originated in ancient Mesopotamia during the fifth millennium B.C., probably originally as potters’ wheels. The wheel’s efficient use of energy must have been quickly understood by its inventors because it was almost immediately set to work in other contexts, most importantly in transport (vehicles) and in foodstuff processing (mill wheels). The earliest undisputed depiction of a wheeled vehicle (here a wagon with two axles and four wheels) is on the Bronocice pot, a ca. 4000 B.C. clay pot excavated in southern Poland.
Early wheels were simple wooden disks with a hole for the axle. The oldest such wheel, dating from the late fourth millennium B.C., as found at the Ljubljana Marshes in Slovenia in 2002. The spoked wheel was invented more recently, and allowed the construction of lighter and swifter vehicles. The earliest known examples appear in the context of the Andronovo culture, dating to ca. 2000 B.C. Shortly later, horse cultures of the Caucasus region were given a tremendous boost by their state-of-the-art horse-drawn spoked-wheel war chariots. The spoked wheel was in continuous use without major modification until the early twentieth century.
A tire is a device covering the circumference of a wheel. It is an essential part of most ground vehicles and is used to dampen the vibrations caused by irregularities in the road surface, to protect the wheel from wear and tear, and to provide a high-friction bond between the car and the road to improve acceleration and handling. Today most tires, especially those fitted to motor vehicles, are "pneumatic" tires—manufactured from rubber and inflated with air—which were invented in stages in the nineteenth century.
The outer perimeter of the tire, often called the crown, has various designs of jagged shaped grooves in it, known as the tread, which improve traction and handling, especially during rainy or snowy weather. When the tread on the outer perimeter of the tire inevitably wears away from use, reducing the tread depth, the tire should be replaced. The sidewalls are the sections of the tire which are between the crown and the inner circular edges of the tire contacting the rim. The inner rim is called the bead.
The common motor vehicle tire is mounted around a steel rim at service stations or repair shops using a special tire mounting apparatus while the wheel is off the vehicle. After mounting, the tire is inflated with air through the valve stem to the manufacturer’s specified pressure. The rim with the tire mounted onto it makes up the removable wheel, which is attached to threaded studs on the end of the axle using lug nuts. Because tires are not made with perfectly even mass around their circumferance, a special tire-balancing apparatus at a repair shop spins the wheel with the tire to determine where small weights should be attached to the rim to balance the wheel. Tire balancing avoids vibration when the vehicle is driven at higher speeds.
Types of automobile tires:
- Summer tires: Also called performance tires, summer tires sacrifice wet weather handling (by having shallower water channels) and tire life (by being made of softer rubber) for dry weather performance.
- Winter tires: Winter tires typically have fine grooves in the tread designed to grip uneven icy surfaces, and are designed to provide improved performance under winter conditions. They are usually removed for storage in the spring. Dedicated winter tires will bear the "mountain / snowflake pictograph" if designated as a winter / snow tire by the American Society for Testing & Materials. Winter tires will typically also carry the "M&S" (mud and snow) designation.
- All-season tires: All-season tires are designed to perform well under winter and summer conditions. However, the type of rubber and the tread pattern best suited for use under summer conditions cannot, for technical reasons, give good performance on snow and ice. Thus many regard them as a poor compromise between winter and summer tires.
- 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, and tread patters with wider spacing to evacuate mud from the tread.
We hope you find this description of wheels and tires useful. However, it is provided entirely without warranty of accuracy or any other kind.
— Rim & Tire Wholesalers
