J Burns wrote:

I bought a set of tires. Installation included a free alignment
check. The cost of an alignment was substantial.

The chrysler dealership where I get the e-test for my 300m has some sort
of photo/optical alignment measurement system that is composed of a
large tube (maybe 6" diameter, 8 feet long) mounted high across one of
the bay door openings, and something that looks like a truck hubcap that
is clipped to each wheel of the car. And that's all that's done - I
think one wheel at a time. The system is somehow able to know if the
wheels are out of alignment without the car moving or any wheels
turning.

They do this for free - I guess they want to make some money actually
doing an alignment, but only if it's needed. The check itself (or the
equipment itself) must be cheap enough to warrant giving the check for
free.

But yea, tire shops are trying to make some extra money by selling
alignment checks.

Is a free check a gimmick

For a tire retailer - Yes.

If your old tires show uneven wear patterns (not caused by under or
over-inflation) or if the car doesn't drive straight on a flat and
straight road without you needing to steer the car slightly in one
direction or another then yea, it probably needs alignment. Otherwise
you're fine.