Without taking a wheel off and just by holding a rule on the centre cap, it looks like 5 x 110mm. The standard wheels are 7" x 14" by 0.31" out. The suspension and hubs of the ME are bespoke for the car.
One of the MEs has alloys that are said to be from a Volvo, so that might be a starting point.
One of the MEs has alloys that are said to be from a Volvo, so that might be a starting point.