Gravel roads and what they do to your car

Stone chips

Loose gravel gets picked up by tires and flung outward and backward. Your own tires throw it at the rocker panels, the lower doors and the inside of the wheel arches. The car ahead throws it at your hood, front bumper and windshield. The faster everyone is going, the harder those stones hit.

A chip that goes through to bare metal will start to rust once it gets wet, and in Ontario it will get wet and salty soon enough. Look the car over after a gravel drive and touch up any chips that show metal. Clear protective film on the front bumper and hood edge is worth considering if you drive gravel often.

Driving to limit the damage

Most gravel damage comes from speed and following distance. Slow down on loose gravel, which also gives you better control, since gravel behaves a little like driving on marbles. Leave plenty of room behind the vehicle ahead, and when an oncoming truck approaches, ease off and move right where it is safe. Their tires throw a spray of stones.

Mud flaps help a great deal on the rear of the car and the lower doors, which is why many trucks and SUVs have them. If yours did not come with them, they are usually an inexpensive dealer accessory.

Dust gets everywhere

Dry gravel roads in summer throw a fine dust that coats the whole car and gets into door jambs, the trunk seal, the hinges and the engine bay. It also loads up the engine air filter and cabin air filter faster than city driving. If you drive dusty roads regularly, check both filters more often than the standard schedule. Your owner's manual usually lists a shorter interval for dusty conditions.

Wipe out the door jambs and the trunk opening with a damp cloth after a dusty drive. The dust in there is the same grit that scratches paint, and it ends up on your clothes and the seats.

Mud in the wheels and underneath

On wet gravel and dirt roads, mud packs into the wheel wells and onto the underside, and some of it sticks to the inside of the wheel rims. A clump of dried mud inside a rim can unbalance the wheel enough to cause a shake in the steering wheel at highway speed. If you notice a new vibration after a muddy drive, a thorough rinse of the wheels often fixes it.

Mud also holds water against the underbody, brake lines and suspension parts. Rinse it off within a few days.

Cleaning up afterwards

An under-car spray reaches the parts a garden hose cannot. Fast Lane's Luxury Wash pairs it with a rust inhibitor, which is a sensible follow-up after mud and gravel have been at the underside, though it does not repair chips that are already through the paint.

• Rinse the underside and wheel wells first, before the mud dries hard.
• Wash the whole car without wiping off dry dust.
• Clean the inside of the wheel rims if you feel a vibration.
• Wipe out door jambs, the trunk seal and hinges.
• Look for stone chips on the front, lower doors and wheel arches and touch them up.
• Check the engine and cabin air filters if the roads were very dusty.