Winter Driving: Car Care Canada’s winter tire tips

Winter tires are an obvious first step in outfitting your car for the cold season. Click image to enlarge

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Car Care Canada, a non-profit advocacy group that offers research, consumer education and information about the Canadian automotive aftermarket industry, reminds motorists that proper tire inflation pressure as well as tread depth are both critical for good fuel economy, safety, maximum tire life, and proper handling and performance. And in most of Canada, winter tires are a must for safety and handling.

Car Care Canada has created a simple glossary and some tips to help you protect your tires. Some of these are winter-specific and some are just good practice year-round.

Winter tires have an aggressive tread design that provide a better grip while throwing off snow and slush, providing more stability when braking and better vehicle handling.

The rubber compound of a winter tire is relatively soft. The rubber in an all-season tire starts to lose elasticity and harden at temperatures around -8°C to -10°C, greatly reducing grip. At -15°C, this type of tire will have lost all its elasticity, whereas a winter tire will only harden at around -40°C – it therefore retains its elasticity for much longer.

When purchasing/installing winter tires, remember the following:

• Install four winter tires – To help maintain control and stability of your vehicle in icy conditions, always install winter tires in sets of four.
• Mixing tires with different tread patterns, internal construction, and size degrades the stability of the vehicle and should be avoided.
• As a tire wears, snow traction is reduced. Tires that are worn close to the tread-wear indicators have reduced traction and should not be used on snow-covered roads or in severe snow conditions.

• Check your tires more often during the winter months. Tires will lose about one psi of pressure for every five degrees Celsius of temperature drop.
• Keep an accurate tire pressure gauge in your car’s glovebox (many gauges at “air stations” give false pressure readings) and check the tire pressure when the tires are cold. Never trust the appearance of a tire as a gauge for inflation. A tire could be 10 psi low on pressure and not appear to be low on air.
• Use the recommended inflation pressure listed in your vehicle’s owner’s manual or on the inflation sticker found on the driver’s doorjamb. While you’re at it, don’t forget to check the spare. There’s nothing more annoying than a flat spare when you have a flat tire.

Regular tread depth checks are important to ensure that your car’s tires are safe. Excessive wear can result in a loss of traction, especially on wet and slippery roads. Tires are regular wear items and staying on top of their condition not only ensures your safety, but also gives you the opportunity to plan ahead and budget for inevitable tire replacement.

The simple way to measure tread depth is with a tread depth gauge. Tire wear bars are also used on today’s tires as a hands-off visual indication that a tire needs replacement.

• When using a tread depth gauge, tires need to have at least one-fifth of a centimetre of tread or more.
• Generally, it’s best to replace tires in sets of four.
• If your car’s tires show signs of abnormal or unequal wear, have this looked into by a professional technician. Excessive wear on both outer edges generally indicates under-inflation. Excessive wear in the centre of the tread generally indicates over-inflation. Cupping or dipping of certain tread sections may indicate worn suspension parts or a wheel balance problem. Saw-toothed or feathered tread edges may indicate wheel misalignment.

“Proper tire inflation pressure and tread depth are critical for good fuel economy, safety, maximum tire life, and proper handling performance,” said racecar driver and Car Care Canada spokesperson Kelly Williams.

Properly maintaining your tires will increase their life. It is extremely important to check your tire treads for signs of wear. Proper treads allow for normal handling of your vehicle and help prevent skidding and hydroplaning. Tires are manufactured with a “wear bar” that tells you when there is less than 1.6 mm (2/32 inch) of tread depth remaining – when you see this wear bar, the tire must be replaced. You could also try the penny test: place a penny in the tire’s groove with the Queen’s crown facing down. If you can see the top of the Queen’s crown, the tire needs replacing.

From Auto Tech, October 4, 2006 (click here to read article)

Tires typically have between 11 and 13 mm of tread depth when new. There are raised bands of rubber on the tire casing that sit 2 mm higher than the base tire. When these bands start to show across the face of the tread, the tire is worn to 2 mm tread depth, which is the legal minimum. Less tread than that will be very slick on wet surfaces and the vehicle can quickly lose control.

While more than 2 mm of tread will work well on good road surfaces, mud or snow traction requires a deeper tread. Some tire manufacturers are building “snow” bands into their winter tire designs. Just like the 2-mm minimum tread-depth wear-bands, these snow-bands are raised rubber across the tire face about 6 mm above the tire casing. Markings on the tire sidewall indicate where these bands are located on the tread, but you can also see them if you look at the tread. Tread depth less than this 6 mm height will not have optimum traction on snow or mud. For best winter traction, replace the winter tires at the beginning of snow season. Once they are worn beyond the 6 mm tread depth, the tires can still be used and are good for wet spring and fall roads, but replace them again before the snow flies the next winter.