Welcome to the skinny tyre riders club.
Standard rims would be 19" WM2, however the factory or the tyre manufacturers later on recommended WM3 on the rear for a larger foot print.
There are a few other options and combinations, 18" both ends, 19 front 18 rear. Rim widths vary too from WM2 to WM4 to suit tyre choice from 90 to 120, the choice is yours. If you feel you must go from the standard fitment this forum will indeed help you with the decision.
Have fun,
Cash