Curbing Your Wheels Is the Law. It Also Costs You Parts.

Curbing the wheels on a hill is not optional here, and it is a genuinely good rule — a parked car that slips should climb the curb rather than roll into an intersection. What nobody mentions is that the maneuver, performed the way most drivers perform it, works three systems harder than ordinary driving ever does.

The rule itself, briefly

On a downhill grade the front wheels turn toward the curb. On an uphill grade they turn away from it, so the tire rolls back against the curb if the car moves. The requirement applies on any appreciable grade, which in practice means most of the city, and enforcement is real rather than theoretical.

None of that is in dispute. The issue is how the wheels get there. Turning the steering while the car is stationary, at full lock, against the resistance of a loaded tire, is the hardest thing you can ask of a steering system, and doing it two or three times per parking attempt several times a day is a load the engineers did not weight heavily.

Tires take it first

A stationary turn scrubs the tire sideways across pavement instead of rolling it. That tears rubber off the shoulder blocks, and shoulder wear is the pattern most owners here see long before the center of the tread is anywhere near worn out. A tire replaced for shoulder wear at half its rated life has usually been parked, not driven, into the ground.

The more serious damage is at the sidewall. Pushing a tire against a curb at an angle pinches the sidewall between the concrete and the rim, and the sidewall carries no protective tread. A pinch can break internal cords while leaving the outside looking almost normal, and the result is a slow bulge that appears weeks later. A bulge is not repairable. That tire is finished, and it will fail suddenly if it is ignored.

Wheels themselves suffer cosmetically and sometimes structurally. Alloy rims scrape easily, and a hard enough contact can bend the flange where the tire seals, which shows up as a slow leak that no amount of sealant fixes.

Steering and alignment

Older cars with hydraulic power steering have a pump that reaches maximum pressure at full lock, and holding it there makes the fluid heat rapidly. A brief moment is harmless. Habitually parking a car at full lock while the engine idles will cook the fluid, and cooked fluid takes seals and the pump with it. If you hear a groan when the wheel reaches its stop, the system is telling you it is at its limit.

Electric power steering, standard on most cars built in the last decade or so, does not have that failure mode. It has a different one: the assist motor draws heavily during stationary turns, and some vehicles will reduce assist temporarily to protect it. A wheel that suddenly feels heavy during a parking maneuver is usually that, not a fault.

Alignment drifts from the impacts rather than the turning. Tapping a curb hard enough to stop the car is a lateral shock through the steering arm and the suspension, and toe settings move a fraction each time. The symptom is a car that tracks slightly off center or wears the front tires unevenly across a year, and it is one of the most common findings on vehicles that live on city streets.

How to do it without the damage

Turn the wheels while the car is creeping rather than stopped. Even a walking pace lets the tire roll into the new angle instead of scrubbing, and it removes almost all of the strain in one change of habit. Ease off before the steering hits its stop, then let it settle back a fraction.

Approach the curb at a shallow angle and let the tread face touch first, not the sidewall corner. Stop on contact rather than pressing against it — the tire only needs to be positioned to catch, not wedged.

Look at your front tires every few weeks, and look at the inner shoulder specifically, since that is the face you never see. Run a hand around the sidewall for bulges. Bring the car in for an alignment check if it has taken a solid hit or if the steering wheel is no longer straight on a level road. San Francisco Auto Repair is on Geary Boulevard in the Richmond and can check the whole front end at once, which is more useful than replacing one tire and waiting for the next.