I want to equip my Koga Miyata Gents Racer with new (tubelesstubular) tyres. The rims are Mavic Monthlery Route Tubular Rims for which I have found the outer width to be 22mm (although I have found some sites claiming it is 21.5mm). I figured that I could put 22mm tyres on it but am now struggling to find the correct tape for it. The inner width was nowhere to be found and I am unsure on how to measure it, as the rims don't have an inner edge but just curve.
So my question is which tape width I need here. Here's a picture of the rim: