my spare is also a 17 and I have normally 18s, i had the occasion to use my spare a month or so ago and luckily it was drivable and only had to go a few miles to the tire shop to get my regular tire replaced..

However, when they pulled off the spare they had found nails in it (I had never used the spare, since I just bought the car CPO in december)

i was lucky, but everyone should check their spares, you never know when you might need it