Tires have two functions:
1) they are air-filled cushions that absorb most of the shocks caused by road hazards and 2) tires grip the road to provide traction.
Two basic tire types: 1) Bias ply which is criss-crossed and 2) radial ply which plies are parallel to each other and perpendicular to the tread.
Never mix bias and radial tires on your vehicle.
By law, details about each tire must be molded into both sidewall.
Metric system: (i.e P 185/70 R 14) starts with “Passenger”, then width in millimetres, then profile (% height/width), then radial construction and finally rim diameter in inches.
Alphanumeric specifications (i.e G R 78 – 14) starts with load rating, “G”, than radial construction, then profile (% height/width) and finally rim diameter in inches
Tires marked “M+5”, also known as all-season, continue to provide safe all-weather performance but may not be suitable for harsh snow or cold conditions. They suffer traction loss due to cold temperature at -8 to -10 Celsius. Also, they lose elasticity by -15 Celsius. Snow tires are made of softer compounds and lose elasticity at -40 Celsius and have unique tread designs that are 40% deeper to provide better traction.
Most tires have built-in tread wear indicators which are filled-in sections of the tread grooves, when the tread has worn down enough to show the indicators as a line of rubber across the tread the tire should be replaced.
Properly inflated tires produce the largest “footprint” with the pavement and give the best traction. Rely not on your eyes but a good tire gauge for accuracy.
The amount of wear a tire gets depends on its location on the vehicle and the type of vehicle. Turning, accelerating, braking, the slant of the road surface, etc. cause each tire to wear. Therefore, one tire could wear twice as fast as another causing an unequal tire performance. To equalize wear and extend the usage of all tires, the tires should be rotated every 10,000 kilometres.
Changing a Tire
Too many injuries and deaths occur while changing a tire every year. To proceed safely, turn on the hazard lights, position the vehicle on a hard flat surface as far off road as possible and apply the parking brake. Set out reflective warning devices 30 metres in both directions.
To change the tire:
1) take the jack, jack handle, lug wrench and spare tire out of trunk
2) block both of the front wheels and the rear of the wheel opposite the flat using stones or blocks
3) Remove wheel cover, use lug wrench to loosen bolts a couple of turns then raise the vehicle until the flat clears the ground
4) Remove the lug nuts and the flat
5) Install the spare tire and the bolts by hand, tighten the bolts slightly.
6) Lower the vehicle and remove the jack, retighten the bolts.
7) Store the jack, jack handle, lug wrench, wheel cover, flat tire and reflective warning devices in the trunk.
Driving with a compact spare
To save space, most vehicles have an under-sized limited mileage spare.
Do not exceed 80 km/h, avoid sudden change in speed or direction, and be aware of the lower ground clearance while driving with this type of spare.