Under Article 133 of the Bahrain Traffic Law Implementing Regulation, what standard must vehicle tyres satisfy?

1. Tyre condition is checked only at the periodic inspection and when a vehicle changes owner
2. Tyres must carry a tread depth of at least 8.5 mm, measured across the centre of the tread
3. Tyres must be pneumatic rubber in a condition that does not let the vehicle skid, sized to its design and firmly fixed
4. Tyre requirements apply to heavy and public transport vehicles but not to private light cars