Apart from lightweights I know 14 inch rims were fitted from 1977-1981. 15 inch before and after. I had 14 inch on mine for over 10 years and then switched to 15 inch, far more tyres available. Looked up more details in my book Morgan Cars Gold Portfolio 1968-1989. The spec for the +8, 14 inch rims, 6 inch width - and quotes 185/70 x 14. Although I always fitted 195s. There are more available at the narrower width on Black Circles at much cheaper prices.
