Freeze-thaw where it does the most damage
St. Louis sits in the band where the temperature crosses freezing repeatedly through the winter rather than staying below it. That is the worst case for road surfaces: water gets into a crack, freezes, expands, breaks the surface apart, thaws, and traffic finishes the job — over and over.
City streets take it worst because they are patched rather than resurfaced, and the older brick sections have their own behaviour: individual bricks settle and lift, producing a surface that is uneven rather than holed.
The damage from a hard strike reaches further than the wheel:
- The wheel bearing. Races brinelled at the points the balls were loaded. Silent that week, rumbling months later.
- Steering geometry. Camber and toe move when a control arm or strut takes a hit — a pull, a wheel that tramlines, a tyre wearing one shoulder.
- Control arm bushings. Torn under shock loading rather than worn out.
- The strut. A bent rod binds; a knock on rebound and a car that never settles after a crest.
- The rim. Bent, still holding air, still looking fine, producing a vibration nothing balances out.
Two things that check the car
Missouri requires a safety inspection on a two-year cycle for most vehicles, with newer ones exempt for an initial period. Emissions testing applies in the St. Louis area rather than statewide.
That combination is unusual and useful. The safety inspection finds what the roads did — suspension play, leaking dampers, tyres worn unevenly because the alignment has been wrong since February. The emissions test finds what the engine is doing.
Two years between safety inspections is long enough that a pothole in one winter can destroy a set of tyres before anybody looks. Checking alignment after any hard strike is the cheap version of that.
For the emissions half: the test reads the OBD-II system on anything from 1996 onward. A lit check engine light fails it whatever the car is doing, and so does a set of readiness monitors that has not completed after somebody cleared a code. Fix the fault, drive several days of mixed use, then go.
Salt underneath all of it
Winter treatment is heavy, so the pothole damage happens to a car whose underside is also corroding. Brake lines corrode from the outside and fail under pressure without warning; caliper slides seize; wheel speed sensors bond into aluminium knuckles.
The buying rule follows: in a treated climate the removal is the expensive half of a job, so complete hub assemblies beat bearings and loaded calipers beat rebuild kits.
Humidity at the confluence
Two major rivers meet here and the summers are humid. That corrodes connectors and grounds rather than structure, and it lengthens the air conditioning's duty cycle beyond what the temperature implies — most of the compressor's work is condensing moisture rather than lowering temperature.
A fault that behaves differently in damp weather is a connector, not a module.
Checked