Which depth can cause loss of traction for many passenger cars when driving through water?

• A. 6 inches
• B. 2 inches
• C. 4 inches
• D. 12 inches

Answer: (A)

When water covers the road, traction starts to drop as depth increases because the tire must push water away as it rolls. Once the water depth reaches about six inches, most passenger cars can no longer maintain enough contact between the tire and the road. The tire can ride on a thin layer of water instead of gripping the surface, a condition called hydroplaning, which dramatically reduces steering and braking control.

Speed makes this worse, since faster movement gives water less time to be displaced and raises the chance of losing traction even earlier. It’s also why you’re warned to slow down and avoid sudden steering or braking when you encounter such water. If you must drive through shallow water, do so very slowly and steadily, and after you exit the water, test the brakes gently to dry them. Avoid driving through water deeper than about six inches whenever possible, as that depth is where traction loss becomes likely for many cars.