17 in wheels?

Does anybody know what the smallest wheels are that you can fit on the Q7?

18" do fit on a 2010, I use them for winters. 17 might just barely but brakes would be very close to scraping the rim, try-before-buy... looks to me like 1/2" clearance for the 18s. I don't know for sure if the brakes on your 2013 would be exactly the same size.

Wheel size:

2014 18" Jetta OEM wheels (with 225/40/18)
fit on a
2009 Jetta (stock) Wagon (which currently has 16"OEM wheels with 205/55/16)?

Do NOT put Jetta rims on a Q7. The smallest rim (and by far best for winter rubber) is a 7.5J x 18. It takes 235/60 18 XL tires. This is a TRUCK, not a car, and requires 107 V XL tires in summer but can use 107 H winter (with obvious speed restriction).

There are replica wheels available in the aftermarket, but WATCH OUT for offset. These 18s need +53 ET. They exist (a lot of dealers sold them).

18s are the smallest that fit on a Q7.. Ive got 17in Cayenne wheels, but it required liberal use of an angle grinder on the calipers to get em to fit.. Touareg and Cayenne were around NA long before Q7, the older model years had smaller rotors/calipers but I believe by the time the Q7 was on the market they all had a big brake upgrade.

Aside from the unsuitability of Jetta wheels as far as strength, they are a 5 x 112 bolt circle.
Cayenne, Q7, and Touareg all have a 5 x 130 bolt circle.