The distance between the sidewalls of an inflated tire. It's measured in millimetres.
205 mm
Profile
The aspect ratio between the the depth of the sidewall and the width of the tyre. It's measured in percentage points. For example, a profile value of 70 means that the ratio depth/width=0.70.
60
Rim
The outer edge of the wheel itself excluding the tyre that sits on top of it. It's measured in inches and sometimes have an 'R' in front it. For example, R15 means a rim of 15 inches.