Yes, I've got 225 40 18.
There's nothing to stop you using 215s, but for me I'd have to have a really good reason to do that over 225s. Such as... being spazzy low or heavily spaced. As in you really need the extra room.
If you're not spazzy low or heavily spaced, you won't need the room. It'd be pointless. And look a bit silly in my opinion.
Plus you might be limited in what decent tyres you can get in 215s. If I could fit 235s or 245s without rubbing, I would. You need as much grip as you can get above and beyond stock power.