Do I really need four winter tires, or can I just get two on the front of my front-wheel drive van?– PB
If you've got winter tires on your van's front wheels and all seasons on the back, your front tires will stick while your back tires will slide – and your car could spin right off the road.
"The rear tires won't be able to grip as well as the front tires," says Denise Koeth, managing editor of Tire Review, a tire industry magazine. "When braking or turning, the rear tires could break loose, losing traction and causing the van to fishtail."
The rubber in all-season tires starts to get hard, like a hockey puck, at around 7 C. And hard rubber doesn't stick to roads. The rubber in winter tires stays softer at lower temperatures, giving them better traction and shorter braking distances than all seasons when it's cold.
Under normal driving, you might not notice that the back wheels aren't gripping. But if you brake suddenly when it's especially slippery, you'll notice.
"If you have winter tires on the front wheels and hit the brakes, the back tires without the traction keeps going," says Antonia Issa, spokesperson for the Rubber Association of Canada (RAC). "It's unsafe – most tire places will refuse to put on just two."
It reminds me of that Maestro Fresh Wes song from high school. With apologies to Maestro (and my editors) – the front grip is amplified, so just glide, and let your back tires slide.
Another word for fishtailing is oversteer, but both words mean that your van's rear end will skid to one side. And that unintentional donut could make you spin off the road or into another car.
If you switch the tires around – with the two winter tires on the back and the all seasons on the front of a front wheel drive vehicle – the front tires won't grip as well as the winter tires in the rear and you'll get understeer. Again, the result could be a loss of control.
"Understeer is basically when the vehicle keeps moving forward, but the front tires do not respond to any steering input by the driver – making it very difficult to steer the car where you actually want to drive," Koeth says.
You can see a front wheel drive car with two front winter tires lose control at low speeds in a 2007 road test video by Transport Canada, the RAC, and the Automobile Protection Association (APA).
So does a rear-wheel drive vehicle need four winter tires too?
The APA, an industry watchdog, says they do. The steering of a rear wheel drive vehicle can wash out if you have snow tires on the driving wheels only, the APA says. Plus, anti-lock brakes and electronic traction control won't work properly if all four tires aren't the same.
Transport Canada recommends four identical tires on all vehicles. That means all four tires – whether snow tires, all weather or all seasons – should be the same size and make, have the same tread and be worn equally.
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