Purcell Tire & Service in Fenton, MO

The other thing metro driving wears out is suspension, and it does it slowly enough that most owners never notice.

What they notice instead is the tire bill. Worn shocks let the tire bounce rather than holding it against the road, which produces a cupped or scalloped wear pattern a fitter can read across the room. Worn bushings and joints let the geometry move under load, which is why an alignment sometimes will not hold.

Suspension repair is offered here, and the sensible order is suspension first, alignment second, tires third. Done the other way round, you pay for the alignment twice and the tires early.

Delivery vans, service trucks and contractor pickups all live on these roads, and all three wear tires faster than their mileage suggests. Fleet services puts them on a schedule rather than a reaction, with agreed specifications and records that show where the money is going. There is no minimum number of vehicles.

When a set comes off, the wear pattern on it is the most honest diagnostic information available, and it costs nothing to read.

• Both outer edges worn: under-inflation, usually chronic.
• The center worn: over-inflation.
• One edge only: a camber or alignment problem.
• Feathering across the tread: a toe problem.
• Cupped or scalloped patches: worn shocks or struts rather than the tires.

Fitting a new set without reading the old one means buying the same wear again. Ask what the pattern showed, and if nobody looked, that tells you something too.