Wheels and Tires

1. Wheels and Tires Look at e-mail from John under inbox tab, brakes class folder.

2. Objectives • Identify the wheel configurations used on heavy-duty trucks. • Explain the difference between standard and wide-base wheel systems and stud- and hub-piloted mountings. • Identify the common types of tire-to-rim hardware and describe their functions.

3. (Objectives cont.) • Explain the importance of proper matching and assembly of tire and rim hardware. • Outline the safety procedure for handling and servicing wheels and tires. • Identify the different means of balancing tire and wheel assemblies. • Describe brake drum mounting configurations.

4. WHEELS AND RIMS The two general types of wheels used are: • Cast spoke wheels • Disc wheels

5. CAST SPOKE WHEELS

7. CAUTION: Never raise a vehicle with a jack placed under a leaf spring. When the wheel has been raised, use heavy-duty axle stands placed under the axle and do not rely on a hydraulic jack alone. When removing wheel nuts from spoke wheels, loosen the nuts a ½ inch, then hit the wedge with a hammer to break it loose.

8. MOUNT A SET OF DUALS TO A CAST SPOKE WHEEL

14. DISC WHEELS

15. Stud-Piloted Wheel

16. Shop Talk Disc wheel nuts for right side wheels generally have right-hand threads, and wheel nuts for left side wheels usually have left-hand threads.

17. CAUTION: To check and tighten the inner wheel torque, first loosen the outer wheel nuts several turns and tighten the inner nuts and then retighten the outer nuts. To avoid losing the seating of the outer wheel when checking the inner wheel torque, loosen alternate outer nuts, tighten the inner nuts, and retighten the outer nuts. Then loosen the remaining outer nuts, tighten inner nuts, and retighten the outer nuts. OEMs suggest that disc wheels require weekly inspections and torque checks.

18. Hub-Piloted Disc Wheels

19. Hub-Piloted Wheel

20. Shop Talk Learn how to identify stud- and hub-piloted disc wheels: Improper torquing procedure and sequencing of stud-piloted wheels is a major cause of wheel failure. With the cone locknut design, a flat washer is seated directly against the wheel face. The nonrotating washer prevents galling of the wheel surface.

21. TIRE-TO-RIM HARDWARE Single-piece rim (tubeless)

22. Two-piece Split Side rings Three-piece Flange or Continuous rings If any components are damaged the rim must be replaced

23. TIRES Two basic types of tire construction are used in heavy duty applications: bias ply and radial tires. Because of this, tires have become axle specific and can be categorized as follows: • Steering axle • Drive axle(s) • Trailing axles

24. DUALS Dual wheels should not have mismatched tires. The tires on an axle should be of the same construction, tread pattern, and nominal size. Mismatched tires on opposite sides of the same axle can cause drive axle failure by continually working the differential, so if the left duals are radial, the right duals also should be radials. If the vehicle has two or more drive axles, the tires on the drive axles should be either all bias ply or all radial.

25. Using a square to check dual tirematching.

26. TIRE CONSTRUCTION

27. Body Ply, Breaker, and Belt Materials Rib, Lug, High-traction

28. WIDE-BASE WHEELS Increased payloads and fuel efficiency

29. WIDE-BASE TIRES

30. Reduced Rolling Resistance Today, tire manufacturers claim that wide-base singles can replace a set of duals in any application. In addition, they are said to provide equal or better traction than duals along with actually increasing the axle footprint width; this marginally increases stability. Also they reduce the weight of the vehicle.

31. DOT CODES

32. TIRE SIZE Tire size is determined by the type of application intended for the truck. The nominal 22.5-inch and 24.5-inch (572 mm and 622 mm) wheel/tire size are commonly used on Class 8 transport trucks.

33. Shop Talk Revolutions per mile data on the drive axle tires must be correctly programmed to the chassis data bus. Whenever tires are replaced or swapped on a vehicle, ensure that you check and reprogram tire revolutions per mile to the appropriate controller on the chassis data bus. This data is used to calculate and broadcast road speed data to the instrument cluster, engine, transmission, collision warning, and other controllers networked to the data bus.

34. LOW-PROFILE TIRES

35. Tire Terminology

36. Cross-section of a tubeless tire

37. 2

38. TIRE INSPECTION

39. Shop Talk Contrary to the beliefs of some truck drivers, tire pressure cannot be checked with a hammer. The only condition a hammer can identify is a nearly or completely deflated tire. Tire pressures must be checked with a pressure gauge. In fleets where this is not a driver’s responsibility, it must be undertaken by a technician.

40. Mechanical Irregularities

42. Camber

43. Caster

44. Load Distribution

45. Other Causes of Tire Wear All tires are speed rated. Exceeding rated speed creates heat. Excessive heat produced by running a vehicle at higher speeds will shorten tire life. At higher speeds, the tire can become distorted. Higher speeds can cause small cuts to enlarge, causing a blowout. Sprung or sagging axle can cause uneven wear on duals. Unevenly adjusted brakes

46. Regrooving and Tread Depth Tires with the word regroovable molded to the sidewall may be regrooved. These tires, along with recapped and retreaded tires, should never be used as front steer tires. Steer tires must have a tread depth of at least 4/32 inch. All other axles must have a tread depth of at least 2/32 inch.

49. RIM INSPECTION • Excessive rust or corrosion buildup • Cracks in metal • Bent flanges • Deep tool abrasions on rings or in gutter areas • Damaged or missing rim drive plates • Matched rim parts

50. MOUNT TIRE TO RIM