Have fairly tidy stock 14" mx5 wheels from my donor and I notice most seem to be running 13" or 15".

Is there any particular reason not to use the 14's? Perhaps they are limiting in terms of tyre choice?

Im sure it's just to do with the choice as you say.

I use 14" to good effect.

I think its due to either donor or target wheel.

slicks and others are available in 13 or 15 and availability is better.

I still brought R888 and AD048 in 14" so its not a biggie