© Goodheart-Willcox Co., Inc. Wheels and Tires Unit

© Goodheart-Willcox Co., Inc.  Tires perform two basic functions:  act as a soft cushion between the road and the metal wheel  provide adequate traction (friction) with the road surface

© Goodheart-Willcox Co., Inc. Tire Types  Pneumatic  filled with air  internal air pressure pushes out on the inside of the tire to support the vehicle  Tubeless tire  does not use an inner tube  tire and wheel form an airtight unit  Tube-type tire  uses an inner tube to hold air pressure

© Goodheart-Willcox Co., Inc. Parts of a Tire

© Goodheart-Willcox Co., Inc. Tire Construction  There are many design variations:  different numbers of plies may be used  plies may run at different angles  different materials may be used  Three types of tires used on automobiles:  bias ply  belted bias tire  radial tire

© Goodheart-Willcox Co., Inc. 1. Bias Ply Tire  Plies run on an angle from bead to bead  Angle is reversed from ply to ply  Does not use belts  Body of the tire flexes easily  Provides a smooth ride  Plies and tread are weakest  reduces traction at high speeds  increases rolling resistance

© Goodheart-Willcox Co., Inc. Bias Ply Tire

© Goodheart-Willcox Co., Inc. 2. Belted Bias Tire  Bias tire with belts added to increase tread stiffness  Belts lie under the tread area only  Two stabilizer belts and two or more plies improve tire performance  provides a smooth ride and good traction  reduces rolling resistance

© Goodheart-Willcox Co., Inc. Belted Bias Tire

© Goodheart-Willcox Co., Inc. 3. Radial Ply Tire  Plies run straight across from bead to bead  Stabilizer belts lie beneath the tread  Belts can be made of steel, flexten, fiberglass, or other materials

© Goodheart-Willcox Co., Inc. Radial Ply Tire  Uses a very flexible sidewall with a stiff tread  provides a very stiff footprint  improves safety, cornering, braking, and wear  may produce a harsher ride at low speeds

© Goodheart-Willcox Co., Inc. Radial Ply Tire

© Goodheart-Willcox Co., Inc. Tire Sidewall Markings

© Goodheart-Willcox Co., Inc. Tire Size Alpha-Numeric–Uses letters and numbers to denote tire size in inches and its load-carrying capacity in pounds

© Goodheart-Willcox Co., Inc. Points of Measurement

© Goodheart-Willcox Co., Inc. Aspect Ratio Height-to-width ratio of a tire. Comparison of a tire’s height and width

© Goodheart-Willcox Co., Inc. Maximum Load Rating  Amount of weight the tire can carry at the recommended inflation pressure  Printed on the sidewall  P-metric:  given in kilograms and pounds  Alpha-numeric:  indicated by a letter such as B, C, or D

© Goodheart-Willcox Co., Inc. Maximum Inflation Pressure  Highest air pressure that should be pumped into the tire  Many tires have a maximum recommended pressure of 32 to 40 psi (220 to 275 kPa)

© Goodheart-Willcox Co., Inc. DOT Serial Number  Identifies the manufacturer, plant, location, construction, and date of manufacture  Stamped into the sidewall  Department of Transportation rating means the tire has passed prescribed safety tests

© Goodheart-Willcox Co., Inc. Speed Rating  Maximum allowable sustained road speed a tire can safely withstand without failure  Ratings range from B to Z  “B” rating 31mph or 50 km/h  “Z” rating 149 mph or 238 km/h

© Goodheart-Willcox Co., Inc. Wear Bars When too much tread has worn away, solid rubber bars will show up across the tread

© Goodheart-Willcox Co., Inc. Compact Spare Tire This is a high pressure spare, requiring 60 psi

© Goodheart-Willcox Co., Inc. Self-Sealing Tires  Coating of sealing compound is applied to the liner  If a nail punctures the tire, air pressure will push the soft compound into the hole to stop air leakage

© Goodheart-Willcox Co., Inc. Self-Sealing Tire Action A. Nail punctures tire B. Nail is pulled out C. Sealing compound flows into the hole

© Goodheart-Willcox Co., Inc. Tire Inflation Monitoring System  Often used with run-flat tires  Pressure sensors are mounted on each wheel  If tire pressure is not correct, the wheel sensor produces a radio signal  Signal is received by a module that turns on a dash warning light

© Goodheart-Willcox Co., Inc. Pressure Sensor

© Goodheart-Willcox Co., Inc.  Designed to support the tire while withstanding loads from acceleration, braking, and cornering  Made of steel, aluminum, or magnesium  Lightest weight is desirable to reduce “unsprung” weight, improving handling

© Goodheart-Willcox Co., Inc. Wheel Assembly

© Goodheart-Willcox Co., Inc.  Valve stem  pressed into a hole in the wheel of a tubeless tire to allow inflation and deflation  Valve core  spring-loaded air valve that is threaded into the valve stem  Valve cap  protects the air valve and stem threads from dirt, moisture, and damage

© Goodheart-Willcox Co., Inc. Valve Stem Assembly Valve stem snaps into the hole in the wheel Press fit forms an airtight seal Valve core screws into the valve stem body

© Goodheart-Willcox Co., Inc.  Lug nuts  hold the wheel and tire assembly on the vehicle  Lug studs  special studs that accept the lug nuts  Lug bolts  used instead of nuts  screw into threaded holes in the hub or axle flange

© Goodheart-Willcox Co., Inc. Lug Nut and Stud Stud is pressed into the hub or axle flange If metric or left-hand threads are used, markings will normally be given

© Goodheart-Willcox Co., Inc.  Small lead weights  Attached to the wheel rim to balance the wheel-and-tire assembly  Used to offset a heavy area of the wheel and tire

© Goodheart-Willcox Co., Inc.  Allow the wheel to turn freely around the spindle, in the steering knuckle, or in the bearing support  Most wheel bearings are tapered roller bearings or ball bearing

© Goodheart-Willcox Co., Inc. Tapered Roller Bearing Lubricated with high-temperature grease

© Goodheart-Willcox Co., Inc. Ball Bearing Balls allow parts to rotate with a minimum amount of friction and wear