They're 17s. Wish that I had 18s sometimes but at least tyres are cheaper!
My VRS came with 18inch wheels, they look the same as your wheels, do they also make them in 17inch then ?
i've seen one fall off in the past (1/2 the disc that is) but the owner did notice and stop/never drove the car)
It was my mate sister's XR3 and was very long tome ago now (20yrs)