Checklist for tires Air Pressure Check the pressure in your tires at least once a month and before long trips. Test air pressure when the tires are cool (after the vehicle has been stopped for at least 3 hours and driven less than one mile). Never bleed or reduce air pressure when tires are hot. Alignment of Vehicle A wheel alignment adjustment may be necessary if the vehicle pulls to the right or the left when the steering wheel is in the straight ahead position. Uneven tire wear is another indicator of the need for an alignment check. All Season Tires All season tires can be used throughout the year. The following markings appear on the sidewall of the tire: M+S, M/S or M&S. This meets the RMA definition of a mud and snow tire. However, there are also tires designed for severe snow conditions. These tires will show a symbol of a mountain with a snowflake next to the MS letters. Asymmetrical Tread The tread of a tire which has different shapes and sizes of grooves in the same tire. Balancing At high speeds, tires generate enormous centrifugal forces. Even tiny irregularities of only a few grams in the tire are multiplied by many orders of size.?Such imbalance stresses tires and suspension. This weight irregularity can be tested and identified at tire dealerships and is balanced by adding small counter-weights.?Every time a tire is fitted to a wheel, it should be balanced. Bead The bead of the tire is that part which sits on the rim. At the center of the bead is the core, which comprises a bundle of steel wires embedded in rubber. This provides a safe and solid seating of the tire on the rim. Camber The purpose of wheel camber is to reduce friction during cornering. The camber is measured when the wheels are standing on a flat surface. The difference from the vertical (inward or outward tilt of the tire) is then referred to as either positive or negative camber. DOT Serial Number The DOT symbol certifies the tire manufacturer's compliance with the US Department of Transportation tire safety standards. The DOT serial number is located on the lower sidewall of the tire, on one side only. Below is a description of the serial number. Starting in the year 2000, four numbers are used for the Date of Manufacture, first two numbers identify the week and the last two numbers identify the year of manufacture. Prior to year 2000, three numbers are used for the Date of Manufacture, first two numbers identify the week and the last number identifies the year of manufacture. To identify tires manufactured in the 90s, a decade symbol (a triangle on its side) is located at the end of the DOT serial number.? For Example: DOT NJ HR 2AE2 529?529 = Date of Manufacture, 529 (52nd week of 1999) or 5200 (52nd week of 2000).?2AE2 = Tire Type Code (coding for type of tire optional by manufacturer).?HR = Tire Size Code Number.?NJ = Manufacturer's Plant Identification Code.?DOT = Reference Symbol (certifies the tire manufactures compliance with U.S. Department of Transportation tire safety standards). Load Index, Ply Rating or Load Range These symbols are found on the sidewall of the tire indicating the load-carrying capacity of the tire. Mixing Tires It is recommended that all four tires be of the same size, construction and speed rating. If tires of different speed rating are mounted on a vehicle, the vehicle speed capability will be limited to the lowest speed-rated tire on the vehicle. It is recommended that the lower speed-rated tires be placed on the front axle. This should be done to prevent a potential over-steer condition. Vehicle handling may also be affected. Consult the tire manufacturer. Radial Tires Radial tires have body cords that run across the tire nearly perpendicular to the beads. Radial tires have belt plies, which are laid diagonally under the tread to stabilize and strengthen the tread area and add flexibility to the sidewall. By restricting tread movement during contact with the road, the belt plies increase tread life, traction and improve handling. Speed Symbol Speed ratings for tires are identified by means of a speed symbol shown on the sidewall of a tire. Although a tire may be speed rated, tire manufacturers do not endorse the operation of any vehicle in an unsafe or unlawful manner. Furthermore, tire speed ratings do not imply that a vehicle can be safely driven at the maximum speed for which the tire is rated, particularly under adverse road and weather conditions or if the vehicle has unusual characteristics. Speed ratings are based on laboratory tests which relate to performance on the road, but are not applicable if tires are under inflated, overloaded, worn out, damaged or altered.?Example: Tire size P215/60R15 H 185/65 R 15 H: the H indicates a maximum permitted speed of 130 mph. Tire Gauge An instrument for determining the pressure in a tire. Tire Size Designation The dimensions of a tire are detailed on the sidewall.?In the case of a P185/65R14 tire, the figures mean the following: 185 = width of tire in mm; 65 = the ratio of the height to the width as a percentage; R = radial construction, 14 = diameter of the rim in inches. Toe The toe describes the distance between the centerlines of the tires on an axle. The toe setting can be adjusted on all cars.? Tread The tread is that part of the tire with the groove pattern which is in contact with the road. The tread is specifically design to provide traction for stopping, starting, cornering and providing long lasting wear. Tread Depth The measured distance from the tread surface to the bottom of the main grooves away from the tread wear indicators 1/32 of an inch. Tread Wear Indicator (TWI) Tread wear indicators (“wear bars”) are located at the base of the main grooves and are equally spaced around the tire. Always remove tires from service when they reach a remaining tread depth of two thirty-seconds of an inch (2/32”). Uniform Tire Quality Grading (UTQG) Made up of 3 components: *Treadwear?The treadwear grade is a comparative rating based on the wear rate of the tire when tested under controlled conditions on a specified government test track. ?*Traction?Traction grades, from highest to lowest, are AA, A, B and C. They represent the tire's ability to stop on wet pavement as measured under controlled conditions on specified government test surfaces of asphalt and concrete.?*Temperature?The temperature grades, from highest to lowest, are A, B and C. These represent the tire's resistance to the generation of heat when tested under controlled conditions on a specified indoor laboratory test wheel. Valve The valve, fitted in the wheel, ensures that the tire can be filled with air. The correct valve is required for the correct wheel/tire assembly; this is the job of the tire dealer. The cause of a slow loss of air pressure can be a defective valve. Valve Cap The valve cap, although small, has a very important job: it protects the sensitive valve internals from dust, dirt and humidity. If valve caps are lost, they should be replaced immediately in order to avoid expensive damage later. __
