I tried getting a good measurement with my caliper, but the flexibility of the tire doesn't help much. Let's say I have a 26"x2.125" tire. I know this fits on an ISO 559mm bead seat diameter rim, and 26" = 660.4mm.
- The OD of the tire including the tread?
- The OD of the tire excluding the tread?
- When aired up or deflated?
- Means it fits a 559mm ISO BSD
- None of the above?
- Width of tread?
- Width of sidewall?
- Inflated or deflated?
Essentially, I'm converting the tire sizes to "height off rim in mm" and drawing them with a wheel in a web application, so I need to know how "tire size" translates to this measurement. I'm somewhat assuming that the fractional sizes can be converted to the same measurement, but I'm aware that they have certain differences - so any help there would be of value as well.
Sheldon Brown's Website has been helpful, but still leaves me with the questions above.