About Tyres: tread, size and damage each count separately: which statement is WRONG?
Tyres may not show damage where the carcass is visible, independent of how much tread remains.
Driving a vehicle that causes or may cause danger on the road is prohibited at all times, not only on the day of the APK.
You may always fit different tyre sizes on one axle, as long as both tyres individually have enough tread.
The tread must be at least 1.6 mm, WITH THE EXCEPTION of wear indicators.
Explanation
trap: only-tread-counts. VekaBest p.204 — tyres on one axle must have the same size designation, except when an emergency or spare wheel is used. Enough tread on both tyres alone is therefore not sufficient