Glossary

Section width

Last reviewed: 2026-05-20

The distance between the outer sidewalls at the widest point of an inflated, unmounted tire, measured in millimeters on metric-designated tires. In the size 295/75R22.5, "295" is the nominal section width in millimeters. For older alpha-numeric sizes like 11R22.5, the width is expressed differently — "11" refers to the nominal width in inches, approximately 279 mm. Section width determines whether a tire fits within fender clearances, maintains adequate spacing in a dual assembly, and falls within the tire manufacturer's approved rim width range. A tire's actual inflated section width may differ slightly from the nominal width depending on the rim width it is mounted on.

Section width determines whether a tire fits between fenders and dual mates without contact under load — and whether it falls within the tire manufacturer's approved rim width range. A wider tire mounted on a rim outside its approved range will have an altered section width and can affect bead seating, sidewall shape, and load capacity. When comparing an 11R22.5 and a 295/75R22.5 for the same position, the 295 is slightly wider — both tires may fit the same rim, but the dual spacing measurement changes and should be verified.

Real-World Use

A fleet manager evaluating a switch from 11R22.5 to 295/75R22.5 on drive axles identifies the section width difference — approximately 16 mm wider for the 295 — as a primary concern for dual spacing. A technician measures the clearance between dual tires with the current 11R22.5 setup, then mock-ups the 295s to confirm dual spacing still meets the tire manufacturer's minimum requirement. The overall diameter difference also needs to be confirmed against fleet specifications before the switch is approved.

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.