the middle number is the profile of the tires. so yea, your 16 inch tires WERE bigger, but since you put on larger rims, it's likely they put on tires with a lower profile to keep the overall wheel diameter the same (which they do for safety reasons).
My 17s are 225/55R17, so don't worry too much about it.
In nomine Patris, et Filii, et Spiritus Sancti. Amen.