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

Mixing tyres on the same axle

What is illegal

You are not allowed to mix different constructions on the same axle. In particular, putting a radial and a crossply tyre on the same axle is both illegal and a safety risk.

What is legal but not recommended

While mixing different brands or tread patterns on the same axle is not specifically illegal, it is highly discouraged. Different tyres can provide different levels of grip, which may lead to abnormal or erratic handling. For optimum safety and performance, it is recommended that both tyres on each axle be of the same brand, size, tread pattern, and ideally the same level of wear.