What it actually does
An alignment resets your suspension's geometry — the precise angles your wheels sit at — so all four tires make full, even contact with the road instead of riding on one edge.
Why it's a safety issue, not just a wear issue
A misaligned car pulls to one side, brakes less predictably, and loses grip exactly when you need it most — in the rain, in a sudden stop, in a turn. Even contact patches aren't cosmetic, they're what your traction depends on.
Get one every time you buy new tires
Brand new tires on a misaligned car will feather and wear unevenly within months — you'll pay for the tires twice. Ask for an alignment check whenever you buy a full set.
Also get one checked if you notice
The car pulling to one side, the steering wheel off-center while driving straight, or uneven wear appearing on tires you already own — any of these mean it's worth a check between tire purchases too.