I made this some time ago. Maybe it could be of help.
![[Image: wheel1.png]](http://www.brickshelf.com/gallery/MagFors/LDraw/pictures/wheel1.png)
0 // On this tyre, 3139, it is:
0 // Nomenclature: width_(mm)/profile_as_%age_of_width x rim_diameter_(mm)
0 // width = 10 ldu x 0.4 mm = 4
0 // profile = (8 ldu / 10 ldu)x100 = 80
0 // rim = 20 ldu x 0.4 mm = 8
0 // Tyre 4/ 80 x 8 Single Smooth Type 1
See also my attached file.
0 // On this tyre, 3139, it is:
0 // Nomenclature: width_(mm)/profile_as_%age_of_width x rim_diameter_(mm)
0 // width = 10 ldu x 0.4 mm = 4
0 // profile = (8 ldu / 10 ldu)x100 = 80
0 // rim = 20 ldu x 0.4 mm = 8
0 // Tyre 4/ 80 x 8 Single Smooth Type 1
See also my attached file.