While it is legal to put tyres with different tread patterns on a vehicle, it is recommended to at least retain the same tyre brand, tread pattern and specifications across the same axle. In other words, the two front tyres should be the same and the two rear tyres should be the same. The tread pattern of a tyre controls how the car grips to the road, disperses the water and generally how the car handles. It is unlikely that tyres with different tread patterns would cause any issues with the driveline. Ideally though, it is recommended to change either two or all four tyres at a time. It is also important to ensure the tyres have the same size, speed and load rating.