The spare tire pan is even different, at least the VAG part number is.....
Never seen a 185/75/80 pan next to a 205/70 pan to compare but assume the
pan for the 205/70 series tires is slightly deeper. As Dennis wrote, The
rods that trap the tire in the spare holder are shaped to accommodate the
larger width of the 205 tire..... and the hoses specified for the 205 tire
are shaped to keep them from being pinched by the spare tire as the assembly
is lifter, clicked and bolted home.

Looked into this a while back when I changed to 16in rims with 215/65series
tires.  Embarrassed to admit, I still have not tried one of the 215/65X16"
wheel-tire combinations in the spare tire carrier! Still have the 14" steel
rim and original 185/80 Vedistrdgjdflgjflj sp??? tire as a spare. Sorry, I
am rambling here.
regards Phil Z.