A Dartmouth woman's experience having winter tires installed on her front-wheel drive car is highlighting a misconception about where new tires should go.

Susan Hachey drives a 10-year-old Toyota Echo. She took her car to Costco in Dartmouth to have winter tires, two older and two newer, installed.

She never thought anything more about it, until she took her car to her Toyota dealership in Dartmouth for servicing.

"As they were doing the oil change they came out and told me the mechanic was recommending the tires with the better tread be put on the front because it was a front-wheel drive," she said. 

So she went back to Costco and asked them to make the change.

"The guy at the counter said, 'Well no. It's a safety issue. The tires with the better tread go on the back,"' she said.

She pointed out her car was front-wheel drive, but the technician told her it didn't matter because the tires with the better tread always go on the back.

"Living where we live and considering that we have winter every year, I couldn't believe I was getting conflicting information from two reputable organizations," Hachey said.

She did some online research and discovered that Costco's position is supported by many others. The next day she called Toyota and said she was again told they recommend the best tires on front because the Echo is front-wheel drive.

'Tested over and over'

That conflicts with Popular Mechanics, which says there is no question where the best tires should go.

"Whether you own a front-, rear- or all-wheel-drive car, truck, or SUV, the tires with the most tread go on the rear," it says in an online article titled 6 Common Tire Myths Debunked.

Automotive consultant Doug Bethune agrees. He said more than 80 per cent of accidents with front-wheel drive vehicles in the winter are caused by rear-wheel skid or spin-out.

"This has been tested over and over on racetracks," he said. "Tire manufacturers, safety organizations, have done test upon test upon test, and every one of those tests indicate that the rear-wheel spin-out is caused on front-wheel drive vehicles because the best treaded tires are not on the back."

Bethune said much of the vehicle's weight is on the front so the best treads are needed in the back to prevent spin-out if the vehicle hits slush or standing water.

'It's debatable'

But where to place the tires with the best tread is "debatable," according to Tim Manuel, vice president of service operations with O'Regan's, where Hachey had her car serviced.

"Generally our policy is that the best tires would go on the rear," Manuel said.

But this situation was different because the older tires were worn, he said. It was recommended they be put on front because, he said, "there would not be any [front] grip if they were left on the rear, so if you were in any type of ice on an incline then you wouldn't be able to move the vehicle."

Manuel told CBC News that Hachey's car is not safe to drive as it is, but she says she was never told that.

Her invoice shows the tread depth on her older front tires measured 4/32". A depth of 2/32" would not pass a motor vehicle inspection in Nova Scotia. The invoice recommended tire rotation, but made no mention of a safety issue.

Bethune said ideally all tires should have the same tread, but a tread of 4/32" doesn't change the fact the best tires should be in the back. He said putting a tire with a 4/32" tread on the back would increase the probability of hydroplaning or spin-out.

"Front-wheel drive or rear-wheel drive, put them [the tires with the best tread] on the rear," Bethune said, adding the recommendation is based on science, not a perception or an assumption.