The problem with Morgan tyres is that they simply do not wear out unless mileage is colossal. Most owners do less than 10K a year and tyres can easily last many years on such a light car.
We have a friend who was still running the original tyres on his '99 4/4 in 2015, they still had legal tread but were as hard as rocks. We convinced him that it was time to change them and he came back with a smile on his face as it had not only improved the ride but had transformed the 'feel' of the car.