The sound of heavy rain hitting the windshield usually signals it is time to slow down, but if your tires are worn, even a lower speed might not be enough to keep you on the road. When the tread depth gets low, your tires lose the ability to channel water away from the contact patch. This creates a thin layer of water between your car and the asphalt, essentially turning your vehicle into a sled. We see it every spring in Hamburg; a sudden downpour turns a routine drive into a stressful situation because the "shoes" on the car just aren't up to the task anymore.