Having discovered that our 1986 +4 was shod with some tyres which were twenty years old, we went on a rubber hunt.
Not keen on the cheap offerings from wherever they are made, we imported quality Avon ZV7 195/60 R15 from the UK factory. The car is like new after the poor ride and steering we had before.
The tyre dealer said that owners of classics such as Rolls Royce use them on their heavy cars, having had issues with lesser tyres. The quality of Avons certainly enhance the drive of a Morgan.
Not sure where MMC source their OE ZV7's but the rubber hardens after just 5 years (confirmed by tyre date). Unfortunately the highly rated Continental Premium Contact 7's I have now are not available in 15 inch rim sizes although later Plus 4's did have 16 inch rims as an option.