Pretty reliable source.
You can see and compare the actual specs at the hub.
I know from personal experience the MK3 is pretty much open to most variations,as opposed to the MK1/2.
But do stick to the same centre bore size though.
Obviously check out the "other badge" list for the suitable models.
Just leaves the diameter.
Even with 195/65 profile the 15" leaves loads of room so with a low profile the 17" should be fine.
This is another good site-
You can then minimise the effect the change will have on your speedo/odometer.
And your warranty.
If youre going for wider spec then be careful to check clearance on full lock to lock and double check inside each of the four arches for different obstructions etc.
Dont forget locking wheelnuts and watch the potholes.
Inform/pay your insurance company of the mods (or have a set of suspiciously clean steels handy to pop on if the inevitable happens....:whistle