Some "all season" tires are good enough for winter roads in B.C., but not all of them.

That's one reason why Transportation Minister Todd Stone has added the topic of tires to a provincial review of highway safety that includes speed limits.

"It's been almost 40 years since the current definition of a winter tire was actually changed, and tire technology has advanced dramatically, particularly over the last five to 10 years," Stone said Tuesday.

With the popularity of all-season tires and all-wheel-drive vehicles, Stone said there is some confusion about what is acceptable for requirements that took effect Oct. 1 on routes that have winter conditions. Those routes have signs advising drivers to use winter tires or carry chains, and police may turn drivers away if they are not properly equipped.

True winter tires have a symbol of a mountain and snowflake on the sidewall. All-season tires with the "M+S" mark to indicate traction in mud and snow are also permissible, but all tires must have a minimum tread depth of 3.5 mm.

A quick test can be done using a dime. Point Her Majesty's head downward and insert the dime in the tire tread. If the top of the head remains visible, the tire is too worn to qualify for winter conditions. Drivers have a choice of investing in new tires or buying a set of chains.

The transportation ministry has a that includes maps of routes affected by winter restrictions, and tips on how to use tire chains.

Stone said that with 60 per cent of B.C. residents living in areas where winter conditions are not common, he is not considering making winter tires mandatory for all vehicles.