When you're shopping for winter boots, one of the things you check is their minimum temperature rating. Something else that would be good to know, however, is how well they do on ice – and there hasn't been a standard rating system in place for that until now, in the form of the Maximum Achievable Angle (MAA) testing method. Spoiler alert: most of the footwear you can currently buy doesn't fare too well on it.

Developed by a team at the iDAPT labs of Canada's Toronto Rehabilitation Institute-University Health Network, the MAA delivers ratings ranging from one to three snowflakes. These are based on the maximum angle at which the boots are able to maintain grip on an icy surface. One flake is awarded for a slope of seven degrees (the maximum allowable curb ramp incline in the province of Ontario), two flakes for 11 degrees and three for 15.

Here's how the testing is performed, in a nutshell …

At a Toronto Rehab facility called WinterLab, a safety-harnessed test subject wears the boots in question while trying to walk across an ice-covered floor. That floor, along with the rest of the room it's in, can be tilted to the required angles. Once the boots start to slip, their rating is determined.

Of the 98 types of commercially-available boots tested so far, though, 90 percent couldn't even manage a seven-degree slope, so they didn't receive a single snowflake. Additionally, none of them got two or three flakes. That said, some prototype boots have scored that high. Overall, boots with Green Diamond or Arctic Grip soles have done particularly well.

Should you be interested in seeing which boots made the one-snowflake grade, you can do so on the Rate My Treads website. WinterLab can be seen in use, in the following video.