What is the reason for the different pattern?
The reason why the tyres have different pattern, is to create different characteristics in terms of traction, ability to remove water, snow or sleet, ability to handle a multitude of surfaces and maneuvering abilities.
The tread is the combination of blocks and grooves that make up the surface of the tyre. They will work together with the surface that you drive on to achieve the best performance. By varying the tyre tread pattern, you can achieve different characteristics.
Symmetrical and asymmetrical pattern
Asymmetrical tyres tend to have a different tread pattern on the outside and inside edges of the tyre. When you have asymmetrical tyres, it is important that you place the tyres as it was intended. The same goes if the tyres are directional then they have to be placed on the correct side of the car.
Same pattern on all wheels
It is advised to have the same set of tyres on all wheels. If for some reason you have changed just two tyres, try to make sure that you at least have the same tyre pattern on the same axis. So keep them either on the front or the rear axis. Different pattern can in the same way as having very worn tyre on one axis, cause the car to slide and make it difficult to get out of the slide.
Tyres are very important for the cars performance and behavior when we drive. We need to have the correct tyres for the weather and surfaces that we intend to drive on.