Overall Diameter × Section Width × Rim Diameter
An example of a Lawn & Garden tire is 13x5.00-6
Referring to the drawing to the left:
overall diameter is 13 (A)
Section width is 5.00 (B)
Rim diameter is 6.00 (C)
Section Width × Section Height × Rim Diameter
An example of a Go-Kart or hand truck tire size is 5.30/4.50-6
Again referring to the drawing to the left:
Section width is 5.30 (B)
Section Height is 4.50 (D)
Rim Diameter is 6 (C)