Tire Fundamentals R Bortignon 1 Tire Function Provide
Tire Fundamentals R. Bortignon 1
Tire Function Ø Provide traction (friction) with the road surface Ø Provide cushion between the road and the metal wheel 2
Tire Size Ø Letter designates tire type: ü “P” Passenger tire ü “LT” Light truck tire ü “C” Commercial tire ü “T” Temporary/spare tire 3
Tire Width Ø Tread width in millimetres Ø This tire’s width would be 235 mm 4
Aspect Ratio Ø Tire height-to-width ratio Ø Aspect ratio = 75 Ø Sidewall height is 75% of the tire width Ø Aspect ratio of this tire is 235 mm X 75% = 176 mm tall sidewall 5
Construction Ø “R” designates the tire is a radial tire Ø Radial tires have plies that go from bead to bead 6
Rim Diameter Ø Rim diameter is given in inches § 13 = 13” § 14 = 14” § 15 = 15” etc. 7
Mud and Snow Rating Ø M+S stands for mud and snow (used on all-season tires) Ø good all-weather performance Ø may not be suitable in heavy snow Ø driving in snow? tire should have the mountain snowflake symbol Ø meets severe snow standards set out by RMA 11
Confused? • Nokian (a Finnish tire manufacturer) now produces an “All-Weather” tire 12
Treadwear Rating Ø Ø Ø treadwear is given as a number the higher the number, the longer the tire will last 100 = Baseline more than 100 = Better less than 100 = Poorer 13
Traction Rating Ø traction (wet braking test) is given as an A, B, or C rating • • AA = best traction A = intermediate traction B = acceptable traction C = poor traction rating 14
Temperature Rating Temperature is also given as an A, B, or C rating Ø A = best Ø B = intermediate Ø C = acceptable Ø the higher the rating the more resistant to temperature build-up Ø the more a tire heats up, the quicker it wears Ø 15
Inflation & Wear Problems • under inflated: excessive wear on outer tread • over inflated: excessive wear in middle of tread wear bars flush with tread: tire needs replacing! 16
17
Tire Rotation Preferred Rotation Pattern Ø ensures maximum tire life Ø evens out tire wear Ø tires should be rotated every 10, 000 kms Acceptable Rotation Pattern 18
Split Rims • • used on many ¾ ton pick-ups into the early 70’s DO NOT demount, inflate or install in a high school shop! 19
Inflation Cage • This is a MUST if you are inflating a split rim! 20
Center Post Tire Machine 21
Wheel Balance imbalance causes vibration in the vehicle or a steering wheel that shakes wheel tramp wheel shimmy wheel balancers correct this imbalance in the wheel/tire assembly 22
- Slides: 19