Under what circumstances could both cross-ply and radial tyres be fitted to a vehicle?

When heavy loads are being carried.
When towing a trailer in snow.
When driving in slippery road conditions.
When each type is fitted on a different axle.

Explantion: In general, you should fit the same type of tyres all round the vehicle. However if you need to fit a mix of cross-ply and radials, the tyres on any axle should be of the same type.

Theory Tester

Under what circumstances could both cross-ply and radial tyres be fitted to a vehicle?

Techincal Matters