Although the Olympics are being held half a world away, here in Overland Park the Olympic sport of pothole avoidance is the main attraction this week.
Of course it’s a known scientific fact that things get bigger when heated and smaller when cooled. A highway is a series of slabs of concrete poured in sections and covered in asphalt. In between each section is an expansion joint. As the air temperature changes, so does the temperature of the road. As the sections grow, the expansion joints in between will bloat on a hot day and contract on a cold day. This constant changing allows water in and weakens the concrete, therefore causing it to break or flake away on the surface. The asphalt breaks away with it. You can see this phenomenon by looking at the edges of any driveway or sidewalk.
Most highway potholes are depressions in the road surface located near these expansion joints. The edges are always the weakest part of each section. Sometimes the surface underneath will wash away due to rain and snow, leaving nothing substantial to hold it up, so it cracks and breaks off. This is why they seem worse this time of year. In addition, the constant pounding of cars and trucks causes the situation to worsen.
There are a lot of car parts that can be damaged from potholes: tires, wheels, wheel bearings, shocks and struts. Your alignment is the most likely thing to be damaged when you have a close encounter with a pothole. When we see a steering wheel that is off and/or a car pulls right or left, if the tires are not low or damaged, potholes will be the culprit of the misalignment.
I can tell you this about tires and it blows my mind. We will see a car that has an obvious bent wheel with a perfectly good tire, still full of air. The customer usually reports hitting something on the highway and then feeling a wobble. In these cases, the tire will be a high quality Michelin or similar. We will replace the wheel and reuse the tire. Respect the tire! On the other hand, we will see low quality tires with a bubble on the side or a depression in the rubber and the wheel is fine with the same report of hitting a pothole. Quality tires are worth every dime. This is especially true if you don’t have to wrestle your 70 mph blowout to the side of the road. You usually only have to experience that sensation once in life before you begin to pay attention to tire quality and tire pressure.
Occasionally we will replace a noisy but tight front wheel bearing. I love to cut the old ones apart with my pneumatic wiz wheel. If the old bearing has imprints on only one section of the race, I will ask the customer if they remember hitting a pothole on the highway. Sure enough, they even guess the correct side, but surprisingly the incident usually happened months ago.