Although not a problem for the MOT, my local garage did advise that I may want to consider new rubber. Looking at all 4 tyres, only one has a DOT code. The DOT code on that tyre dates it to 1995, 1985 or 1975. The others (all matching Michenin) don’t have a code which has been mandated since 2000. The conclusion is that all 4 tyres are more than 20 years old and possibly closer to 30.
There are numerous horror stories about tyre failure of older tyres at speed, especially on motorways, so I decided to replace them.
The original factory fit tyres were 185/80 R14 which have a rolling circumference of 2047mm. You can’t buy these from a standard tyre shop, only as specialised vintage tyres. Yes some would say that you need to keep the car original. I am a little more pragmatic. I prefer modern tyres in current standard sizes, so they can be easily replaced if required, at any tyre shop, and at reasonal cost.
As the car is now running on 15″ chrome wire wheels, I went for 195/65 R15. A little more rubber on the road and a rolling circumference of 1994mm. This is a variance of 1.67%. which is well within tolerence of the speedo.