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Tire Guide

Tire Talk: Dangerous ‘fenderbergs’ prevent tires from turning

Published March 12, 2014

Could you comment on the importance of clearing the built-up snow in your wheel wells. I’m sure they’re wearing the tires down. Also, when these chunks break off on the highway, it can be very dangerous.

These are sometimes called fenderbergs because, like icebergs, you only see the top layer. The majority is stuck to the top of the inner fender.

It takes very cold conditions for these to build up, plus the road must be wet with slush. The slush is splashed up into the wheel well, where it freezes to the top of the fender liner, suspension and, often, to the inside of the wheel well.

That’s when it can become seriously dangerous. After long periods of going straight, the tire’s ability to turn into a corner can be limited by the ice build-up.

This is an eerie feeling when the car does not want to turn. Some see-sawing of the wheel will help grind away some of the blockage, or stop if you can.

Generally the buildup on top of the tire is not such a problem, since the rotating tire kind of rubs on it, grinding away the surface layer. It is extra friction on the tire, but it is not considered to be a big wear factor.

Part of that may be because these blocks come loose pretty regularly when the car hits a severe bump. That’s why you see bits of fenderbergs scattered on the highway just after a bump or road height change.

However, suspension and tire damage may occur if the fenderbergs get big and become solid blocks of ice. When the car hits a large bump, these can limit the suspension travel and force the tire sidewall to take a much bigger hit than it is designed for.

Another problem is ice buildup between the wheel spokes. If you have been driving in deep snow for a while, forcing the car to plow ahead, snow gets in between the wheel spokes and freezes there.

At slow speeds, it is not an issue; but once you reach highway speeds, the wheels can be grossly out of balance with the weight of the ice. All it takes is a few ounces to throw the wheel into a serious vibration.

So, for both these problems, get in there with your snow brush and start hacking the ice off before it builds up.

I have a question about the factory-supplied tires on my 2011 Ford Fusion and how they compare to today’s durability for tires. The tires show ‘M&S’ — mud & snow. Is this the same as all-weather?

The tires on your Fusion are all-season; they are not the newer generation of all-weather tires.

The M&S designation means the tires conform to the Rubber Association of Canada’s minimum standard for the tread pattern.

Those rules specify several things, the most important being that the tread has a minimum of 25 per cent void area. That means 25 per cent of the tire is open groove, to ensure there are enough biting edges for mud and snow.

There is no performance test for an M&S rating. If the tire has a 25-per-cent void area, it can be branded. This standard is so lax it means nothing.

That’s why the RAC in Canada and the RMA in the U.S. came up with the “Severe Service” logo — a mountain peak containing a snowflake.

For that to be on the tire, it must be tested to a performance standard to ensure it has snow grip. All-weather tires carry this logo pictograph and can be driven all year.

Send tire questions to thetireguy_1@hotmail.com. Mail volume prevents personal replies.

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