Q My 21-year-old son has been driving since he turned 16. He has always been a good, safe driver and he never had a ticket or an accident while driving our front-wheel drive vehicles.
Last April, he bought a used four-wheel-drive Toyota 4Runner. My son has lost control of the vehicle twice while driving in snow. The first time, he was only going 30 to 35 miles per hour but did not have it in 4WD. The second time, he was going 40 to 45 mph in 4WD and felt that it was a safe speed.
Now, he doubts his confidence in the vehicle and in his driving ability. Are there things he needs to know about driving a rear-wheel-drive car that are different from a front-wheel-drive car?
A You didn't say how he lost control -- whether he failed to negotiate a turn and went straight off the road, rear-ended another vehicle while braking, or spun off the road into the ditch -- so I can't comment on specifics. Nowhere in your description are two critical factors -- your son's specific actions precipitating the incidents and the type and condition of the tires.
This isn't what you want to hear, but vehicles don't lose control of themselves. A motor vehicle is just a machine, and it can only respond to the inputs of its driver. The causes of the incidents you've described were "driver error," not vehicle failure. The loss of control was caused by the driver asking for more traction between the tires and road surface than was available at the time.
The simple answer: lower speeds and smoother, more progressive control inputs to keep the required level of traction or grip within the tire's capabilities. Better situational awareness developed by looking farther ahead allows a driver more time and distance to adjust the speed or direction of the vehicle. Slowing down and/or changing directions over a longer period of time and distance requires less traction.
Perhaps the most telling factor in driving on slippery roads is to remember that it requires very little traction or grip from the tires to maintain a steady speed -- whether that speed is 20 or 50 mph -- so we tend to feel artificially secure when driving at steady speeds on slippery roads. It's when the driver needs to change the speed or direction that the demand for traction is greatest.
The answer is to anticipate the need to accelerate, brake or turn well in advance so that control inputs can be smooth and progressive rather than sudden or quick. And make sure the vehicle has good-quality all-season "M&S"-rated tires with plenty of tread.
