Gravel is a few miles away in every direction
Des Moines is a metropolitan area surrounded immediately by one of the largest gravel road networks in the country. For a great many people here, the first or last part of a journey is unpaved even if the commute is not.
Gravel adds abrasion to every failure mode a paved road has:
- Boots and seals. Grit is thrown continuously at every rubber boot on the car. A torn constant-velocity boot on tarmac is a race against time; on gravel the joint has ingested abrasive within the week.
- Air filters. Engine and cabin filters load at rates no service interval anticipates.
- Brake hardware. Dust plus moisture plus winter salt residue becomes a grinding paste around caliper slides.
- Wheel bearings. Water and grit are worked at the seal constantly rather than occasionally.
- Paint and glass, from stones thrown by oncoming traffic.
Harvest fills the air
Tillage and harvest put a great deal of very fine particulate into the air for weeks at a time, twice a year.
Cabin filters load fastest, and a loaded cabin filter reduces airflow across the evaporator — which reduces air conditioning and heater performance and then gets diagnosed as something more expensive. Engine air filters load too, costing power and economy long before anything appears on the dashboard.
Check both by looking rather than by counting months. In this region it is the cheapest maintenance decision available and the one with the most obvious result.
Storms that are genuinely destructive
Iowa gets damaging hail most springs and, less predictably, derecho events — straight-line wind storms strong enough to do structural damage across a wide area.
For a car that means lenses and fins. Hail cracks a polycarbonate lamp lens without shattering it, water gets in, and the assembly fails weeks later. Both hail and wind-driven debris flatten condenser and radiator fins, which reduces the ability to reject heat.
Wind events also bring branches down onto parked cars, which cracks lenses and glass in the same way.
Salt on top of grit
Winter treatment is heavy, so the gravel grit and the road salt work on the same vehicle. The salt-belt failures apply: brake lines corroding from the outside and failing under pressure without warning, caliper slides seizing, wheel speed sensors bonding into aluminium knuckles.
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.
Nothing inspects it
Iowa has no periodic safety inspection and no emissions testing. On gravel roads that find every weakness, an annual look-over with the wheels off is the substitute: boots checked at full lock, wheels rocked at 12 and 6 o'clock, pad thickness measured, and brake fluid tested for water content.
Checked