Check my GalleryI would guess as wide as you want. If you mean without handling issues or rubbing, there are several threads on tires and wheels.
17"s on my 451 pics at last!
new pictures with s-mann brakes and redone wheels
Nicest smart I've seen yet. HRE wheels
Just put 17's on my Smart
RIAL's 15" with KUMO 205x50x15"
New wheels/tires have transformed the car
16" Work meister s1 came in.
Look what British Airways brought today!
Black Smann Body with Lorinser Speedy's