Is it permitted to fit a radial tyre alongside a cross-ply (diagonal) tyre, or tyres with different tread patterns, on the same axle of a car or bus?

1. Yes, as long as both tyres hold the correct air pressure.
2. No — mixing a radial with a diagonal tyre, or tyres with different tread patterns, on one axle is a fault that prohibits operation.
3. Yes, but only on the rear axle of a front-wheel-drive car.
4. Yes, during the summer months only.