Pbondar said:
Its technically illegal to have any combination of runflats and normal tyres, either across axles or even front and rear pairs
Where did you get that information from?
Even Michelin state that it is permitted (albeit temporarily):
Can I mix run flat tires with normal tires?
Never mix run flat tires with tires that do not have run flat technology (conventional tires) -
unless in an emergency situation on a limited, temporary basis. The conventional tire should be replaced with a run flat tire as soon as possible.
It is also not recommended to mix different run flat technologies/products together.