When a police officer suggested I keep a glass of salt in my car during winter, I honestly thought he was joking. Salt belonged on dinner tables, not in cup holders. But after watching my tires struggle for grip on an icy street, he explained that this inexpensive household item could solve several common cold-weather problems. Curious, I decided to follow his advice instead of dismissing it as another old-fashioned trick.

A few days later, a freezing morning gave me the perfect chance to test it. My car refused to move as the tires spun helplessly on a patch of ice. Remembering the officer’s advice, I reached for the jar of salt I’d left in the car. What happened next completely changed the way I prepared for every winter drive.