Measuring Rim Width Comparator
Compare the rim each maker used to measure. Use the calculator below. Results update as you type.
How the Measuring Rim Width Comparator Works
This comparator works by listing the measuring rim behind each published tire dimension and estimating how much that dimension changes on your rim. It helps compare spec sheets fairly.
- Enter the tire's published section width and measuring rim, for example 245 mm on 8.0 in.
- Enter your rim width, for example 9.0 in.
- Read the estimated width on your rim: about 255 mm.
- Compare with another tire measured on a different rim.
The Formula
The formula estimates Width Change ≈ 5 mm (0.2 in) per 0.5 in of rim width change.
Width_on_rim ≈ Published Width + (Your Rim − Measuring Rim) ÷ 0.5 × 5.08 mmWorked example: a tire published at 265 mm on an 8.0 in measuring rim, mounted on a 7.0 in rim, is about 265 − 10.2 = 254.8 mm wide.
Conversion Table
The conversion table lists 8 published tire values, whether each depends on the measuring rim and how much it changes per 0.5 in of rim width. Section width changes most; load and pressure ratings do not change.
Use the table to decide which spec sheet values need a rim correction before comparing 2 tires.
| Published Value | Depends on Measuring Rim | Changes per 0.5 in Rim Change | Unit |
|---|---|---|---|
| Section width | Yes | About 0.2 in (5 mm) | in / mm |
| Tread width | Yes | Small change | in / mm |
| Overall diameter | Slightly | Under 0.1 in (2 mm) | in / mm |
| Revs per mile | Slightly | Under 0.3% | revs/mi |
| Static loaded radius | Slightly | Small change | in / mm |
| Load capacity | No | None | lb / kg |
| Max pressure | No | None | psi / kPa |
| Tread depth | No | None | 32nds / mm |
What Is the Measuring Rim Width Comparator?
The Measuring Rim Width Comparator is a tool that compares tire dimensions published on different measuring rims. Tire makers measure section width and overall diameter on a specific measuring rim, listed on the data sheet.
Two tires with the same nominal size can show different widths if they were measured on different rims. The comparator puts both on the same rim for a fair comparison.
Common Uses
This comparator has 4 uses: fair comparisons, clearance estimates, data-sheet reading and fitment planning.
- Compare fairly: Put 2 tires on the same rim basis.
- Estimate clearance: Find real width on your rim.
- Read data sheets: Know which values depend on the rim.
- Plan fitment: Predict width on a planned wheel.