Weekly Hack: Testing tire treads

Published: November 8, 2019

By Krasula/Shutterstock

The snowy season is just around the corner. Or, in cottage country, it may have already arrived. Better slap on the winter tires! But wait, are last season’s wheels still in decent shape? Winter driving wears on a tire’s tread, and without enough tread, a tire can’t grip. This means your car is more prone to skidding, sliding, and hydroplaning—not to mention taking a damn long time to slow down. Annoying. Sometimes terrifying.

Tread depth is typically measured in 32nds of an inch. Most tires start out with about 10/32” of tread. A worn-down tread depth of 5/32” still gives your tires some traction, but it may not be enough to get you through the season, depending on how many kilometres you drive every winter. A measly depth of 2/32” or less, on the other hand, means you should replace the tire. (PSA: driving with insufficient tread is illegal in some provinces.)

For an accurate measurement, you can test tread depth with a specialized gauge. If not, estimate it using the coin tests.

Got a dime? Insert it, with the Bluenose’s sails pointed down, into the grooves between the tire treads. Can you see the tip of the sails? Replace the tire. No, like right now.

Got a quarter? Insert the caribou nose-first. If you can still—just barely—see the tip of the snout, it means the tread is still decent, but the tire may not safely (or legally) last for more than 10,000 km. Test again partway through the winter.

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