As best I can remember earlier +8`s had smaller diameter (Millrace) alloy wheels, with larger aspect ratio ( higher sidewalls) tyres than later +8`s though both wheel and tyre combinations had the same rolling radius thus could be swapped without altering speedo read outs etc.. I never drove both versions to be able to provide comparative differences, however Porsche had a similar wheel tyre choice set of options on the 911, and there was a notable difference in the improved comfort levels with the higher sidewall tyre set-up, on the negative side the steering was less direct due to sidewall flex taking longer to settle into corners which was more noticeable when on a interesting twisty road... Porsche also fitted more sporting shockers to the cars with lower sidewalls which may have added to the difference in feel.... I have no idea if Morgan altered shocker types when changing from smaller to larger diameter wheels.
It seems ever larger wheels with ever lower aspect ratio tyres may be more desired option, perhaps on the basis of style than performance in many cases...I would guess that a CX Morgan may have more possibilities for compliant suspension than a Trad, thus could run more comfortably on lower aspect ratio tyres than a trad..? I guess seat padding may also be a consideration, both one`s own and that of the car..?
It seems logical that round clearance can be improved with larger diameter wheel/tyre combo`s but fitting them under the wings and avoiding fouling steering would seem to have potential to create issues..?
Good luck in your choices.
