PDF files: to store in database or not

With no experience of storing binary data in a bytea column I don't know
when its use is appropriate. I suspect that for an application I'm
developing it would be better to store row-related documents outside the
database, and want to learn if that is the appropriate approach.

Consider an application that manages a fleet of vehicles. There's a
Vehicles table with information on each one (perhaps make, model, VIN, year
of purchase) and a Services table. There are many PDF documents associated
with each row in the tables: purchase contract, insurance form, service and
maintenance records, etc.

My thinking is to not store these documents in the database, but to store
them in subdirectories outside the database.

Your thoughts?

Rich