Auto Tech: Changing Back to Summer Tires

Originally published April 26, 2012

By Jim Kerr; photo courtesy RainyDayMagazine.com

The weather has warmed up again, spring is here and the possibility of snow or ice on our roads is minimal. [Ed.: except in Ottawa, where it snowed Monday. Grrrr…] If you haven’t already done so, it’s time to change over from your winter tires to summer ones.

I highly recommend using winter tires for our Canadian climate and so do the tire manufacturers. This isn’t a plot to sell more tires, because by using different tires for summer and winter you are doubling the length of time each set of tires will last. The reasons for changing back and forth are primarily better traction, which makes your vehicle safer to drive. Tire companies recommend switching tire types when temperatures are about 7 degrees Celsius. While you can use summer tires below that temperature and winter tires above that temperature, you will gain the most benefit by switching when temperatures average around 7 degrees.

Whether you swap tires yourself or have a shop do this for you, it is a great time to do a general safety inspection of the vehicle. With wheels removed, it is easy to see brake lining thickness, oil leaks from struts and shocks, and low-hanging exhaust systems. Of course, it is also a very good time to take a look at the wheels and tires you are using to see if there is any damage or they are worn to the point of needing replacement.

Using a second set of wheels for your other tires is recommended. The initial purchase price of the wheels is quickly offset by the cost of swapping tires on one set of wheels and rebalancing them. It is also quicker and more convenient to swap tires when they are already mounted on wheels. A repair shop may be able to fit you in for a few minutes to swap wheels but it may take a couple weeks wait before they could book you in to remount tires on wheels.

When installing the wheels with summer tires back onto your vehicle, both the back side of the wheel and the mounting surface on the vehicle hub must be clean of any dirt, corrosion or debris. A wire brush or coarse sandpaper can be used to clean the steel parts. Aluminum wheels are softer, so they should be cleaned with a less abrasive product like a Scotchbrite pad. In a pinch, I have even used an old pot scrubber to clean the wheel-mounting surface. If you torque a wheel when there is dirt or corrosion between the wheel and the hub, it can distort the hub and brake rotor, causing a pulsation in the brake pedal. A clean mounting surface and the proper torque are critical every time a wheel is tightened or it can cost you expensive brake parts replacement a few thousand kilometres down the road.

Some driver’s will swap over to performance summer tires. These offer the best grip on warm pavement but often don’t work quite as well in wet conditions. They often also have a softer rubber compound so they wear faster. Most drivers switch to all-season tires, which would probably be more accurately named “three-season” tires. These tires offer a good balance between traction in wet, mud, gravel, and pavement surfaces while providing good tire life.

While you are swapping tires, take a look at the amount of tread remaining on the tire. Most tires will come new with about 11/32 to 12/32 of an inch tread depth. For traction in snow, a tire with 6/32 or more of tread depth works better. When a tire reaches 2/32 of an inch tread depth, it doesn’t have enough tread left to channel water away from the face of the tire on wet roads, so hydroplaning can occur. Hydroplaning is when the tire lifts off the surface of the road and slips on the water, just like a water skier. You don’t have any control when this happens.

To warn the driver that the tread is worn, tires have “Wear Bands” molded into the tread pattern. These bands of rubber are layered into the tread that sit 2/32-inches higher than the bottom of the tread grooves. When the tire is worn, these bands will show as solid rubber strips across the tread, so it is easy to identify wear visually. Planning ahead can save you money on new tires. New winter tires are often introduced in late summer and this is a good time to go shopping. Looking for summer tires in the winter time can provide some good sales, too.