What is the statutory minimum tyre tread depth for heavy commercial buses (>3.5 tonnes) in Austria for summer tyres?

1. 2.0 mm across the entire tread profile under KDV § 7
2. 1.6 mm across the centre three-quarters of the tread
3. 4.0 mm across the tread profile
4. 1.0 mm for rear dual tyres only