'ere you go ****ant...
As well as being slightly smaller diameter and fatter than the original, it is also not as dished, so gives a bit more room for those of us of a larger elk.. whilst still leaving enough room to not be knocking the indicator stalk all the time.
I have kept the original wheel - for those of you who get really upset about these sorts of things, but overall it makes a suprisingly large difference to driving comfort