Well, my curiosity is piqued now so I measured one of my original Dino wheels - as fitted new on a 1971 Dino 246:
it is 193mm wide ( centre line therefore @ 96.5mm)
mounting face of the wheel is 114mm deep
offset is therefore 17.5mm
(as measured with my daughter's plastic ruler, LOL)
Cromodora_CD1_mine.jpg
Cromodoara_CD1_mark.jpg
Cromodora_CD1_1971.jpg
Cromodora_CD1_width_193mm.jpg
Cromodora_offset_calculation-3.jpg
I should add that the distance from the mark on the ruler ( 196mm ) to the base of the ruler sitting on the wheel mounting face is 114mm
cheers
Ross