Quick Example
Mazda's U.S. owner's manuals list 225/65R17 (28.52" diameter) and 225/55R19 (28.74") for the CX-5. Going from the 17 inch size to the 19 inch size is a +0.8% diameter change, inside the common 3% guideline, so the speedometer stays accurate. Mazda says to replace tires with the same type originally fitted, so check any other size with a Mazda dealer. Enter your model and a target size below for the exact number.
OEM diameter: 28.52"
Diameter: 28.63"
Diameter Difference
+0.40%
225/65R17 225/60R18 (+0.11")
Speedo Error
+0.40%
OEM Revs/Mile
707
New Revs/Mile
704
Safe Threshold
±3%
Get a plain-English explanation of your results and what they mean for your vehicle.
Mazda Tire Guide
Full model lineup including MX-5 Miata — see the dedicated Miata Tire Calculator for that model.
Mazda Factory Size Comparisons
| Model | Factory Size | Target Size | Diff % |
|---|---|---|---|
| Mazda3 (2019–2025) | 205/60R16 (25.69") | 215/45R18 (25.62") | -0.3% |
| CX-5 (2017–2025) | 225/65R17 (28.52") | 225/55R19 (28.74") | +0.8% |
| CX-30 (2020–2024) | 215/65R16 (27.00") | 215/55R18 (27.31") | +1.1% |
| CX-9 (2020–2023) | 255/60R18 (30.05") | 255/50R20 (30.04") | -0.0% |
| MX-5 Miata (2016–2026) | 195/50R16 (23.68") | 205/45R17 (24.26") | +2.5% |
Both sizes in each row are listed in Mazda U.S. owner's manuals. Diameters are calculated: Rim × 25.4 + 2 × (Width × Aspect ÷ 100). Always verify against your tire pressure label.
How to Use This Calculator
- Select your Mazda model to load a factory tire size.
- Enter the target tire size you're considering.
- Review the diameter difference, speedometer error, and size-change rating. For a full comparison table of the two sizes, use the tire size comparison calculator, and Mazda spare limits are quoted in the spare tire compatibility chart.