When do you NOT have to make a database from scratch?

This might seem like an obvious question, but I am just getting into doing an actual website (as opposed to a test website in college), and I'm genuinely curious.

A friend wants me to design a website for his business, which is a tire and auto repair shop. I've looked at a few other tire shop designs to get a feel for what he would need, and every site I've looked at has a little section of drop-down lists where you can select your make, model, year, etc. to get a quote on the specific tires you need for a specific vehicle.

Here's my question: Are all these different tire sites just using a general database? Or do they all really have a designer go through and input every make and model and year into a huge database? Like, would you think they are using unique databases or are drawing from some common source?

I know it's a bit of an obscure question, but I think you could apply it to other types of databases as well, where many business sell the same kind of slightly different products.

I'm definitely not opposed to setting up a huge database for him, but I wanted to ask that kind of general question before I threw myself into something like that.

Thanks for any responses!

There are some tools OTS (off the shelf proprietary) that slaughter the database schema (it's a disgusting design), but it works like a freaking charm when it comes down to not even touching SQL... I can't remember what one of them is called, but you can essentially make the user interface with a drag + drop type of tool, and it will handle all of the dirty work on the back-end. The downside is that it's a complete backstop technology, the database design is so convoluted that it's nearly impossible to move to anything else (like... H2, Sybase, or whatever), let alone edit the database by hand-- everything seems like it must be done through their proprietary software.

Unfortunately I don't remember what this software was called :( but it did cost money. I think it ended with "Pro" hahaha :| it even set up the webserver for you, and had many templates which were actually quite useful...

It's not that this is a bad way to do it: if it works for you then more power to you, i'd rather not spend 20 hours when I could have spent 1 hour and gotten the same result. I still believe that if you want something nice, you'll have to put some time/effort into it.