Glossary
Overall diameter
The outer diameter of an inflated, unloaded tire. Determines ride height, fender clearance, gearing effect, speedometer accuracy, and whether two tires can be used together in a dual set.
Match overall diameter closely when checking dual sets. A mismatch of more than about 1/4 inch causes one tire to drag against the other, building heat.
Real-World Use
A fleet switching from 11R22.5 to 295/75R22.5 checks overall diameter because the difference — about 1.5 to 2 inches — affects fifth-wheel height and speedometer accuracy.
What to Pair It With
Read this term with the full tire sidewall, vehicle rating information, manufacturer documentation, and the actual condition of the tire.
This site is for general information only. It does not replace professional tire service, DOT compliance advice, tire manufacturer instructions, vehicle manufacturer recommendations, or fleet policy.