November 3, 2010
By Jim Kerr
This past weekend I changed to winter tires on both my wife’s car and my father-in-law’s car. We haven’t seen snow yet but when average temperatures start to drop below seven degrees Celsius, the extra traction that winter tires have over all-season or summer tires makes changing them worthwhile. I keep the winter tires on their own wheels, so changing them is something I can do myself in an afternoon. A tire wrench, jack, safety stand and a torque wrench to tighten the wheel nuts are all that is required.
A tire pressure gauge is something you should already have, and you will find the winter tires have lost some pressure during storage. This is normal, as tires will typically lose about 1 PSI every month. Even if you have a repair shop change your tires, you should still be checking your tire pressures once a month during the winter.
The benefits of winter tires are well documented and some areas like Quebec have made their use mandatory for winter months. New tires are also better than old ones. As tires age, the rubber becomes harder so it has less grip. This usually isn’t a problem for most drivers, as they will wear the tires out in 3 or 4 years. However, older tires should be replaced. Most experts in the tire industry recommend replacing tires that are a maximum 10 years old, regardless of how much tread is left. If you want to know how old your tires are, look for the tire identification number embossed in an oval on the sidewall. Since 2000, the last 4 digits of the number indicate the week (2 digits) and year (the next 2 digits) the tire was manufactured.
There is more to tire life than just age. The minimum legal tread depth is 2/32 of an inch. When your tires are worn to that point, solid bands of rubber will appear across the tread as a visual cue that the tires need to be replaced. These bands are manufactured into the tread when the tire is made, but you may want to change tires before they get that worn. If you are driving in snow, about 6/32 of an inch is a good minimum for adequate traction. Less tread will not be able to hold snow, and it is really the snow trapped in the tire tread that provides much of the grip to the snow on the road.
Driving on ice is best if the tires have at least 4/32 of tread. Since most tires start out with about 11/32 of tread depth, that means the tires are about three-quarters worn. If your winter tires are worn to that point in the spring, it is best to get a new set for the next winter.
When changing to winter tires, it is also a good time to check the tread left on your all-season or summer tires. If road conditions are good, you can wear them down to the minimum but if you drive on wet roads and through puddles, you will want more tread depth to channel the water away from between the tread blocks and the road. If the water becomes trapped, you get a condition known as aquaplaning, where the tire has no traction on the road at all. An aquaplaning tire has no control and dangerous skids can occur.
Newer vehicles also have tire pressure monitoring systems. When you install winter tires on an extra set of wheels, you also need to install tire pressure sensors. If you don’t, the tire pressure warning indicator will remain lit on the dash all the time. Tires that have been moved to a different position on the vehicle should also have the tire pressure system reset so the computer can identify the correct tire that is low on pressure.
Once drivers experience winter tires on slippery roads, they don’t want to go back to running on all-season tires again. A set of tires is much cheaper than even a small collision so if the tires save you once, they have paid for themselves. Getting them installed now will also beat the rush that occurs when the snow flies. Now it’s back to work for me again. My son’s car needs the winter tires installed, and it is time I show him how to do it.