Is it illegal to have different tyres on the same axle?

Mixing tyres on the same axle

What is illegal

You must not mix different construction types on the same axle. Specifically, fitting a radial and a crossply tyre on the same axle is illegal and dangerous.

What is legal but not recommended

Fitting different brands or tread patterns on the same axle is not specifically illegal, but it is not recommended. Different tyres may have different grip levels, which can cause uneven handling. For the best safety and performance, both tyres on each axle should be the same brand, size, pattern and ideally the same level of wear.