265/70R17 and 275/65R18 differ by about 1.48% in calculated nominal diameter. This is an arithmetic comparison, not an approval to replace one with the other.
Size-code geometry
| Measure | 265/70R17 | 275/65R18 |
|---|---|---|
| Nominal section width | 265 mm | 275 mm |
| Aspect ratio | 70% | 65% |
| Wheel diameter | 17.0 in | 18.0 in |
| Calculated nominal overall diameter | 31.61 in | 32.07 in |
Moving from 265/70R17 to 275/65R18 changes calculated diameter by +1.48%. If a speedometer was calibrated for the first size and reads 60 mph, a nominal ratio would imply about 60.9 mph on the second. Actual rolling circumference can differ.
Different wheel diameters: these two tires cannot mount on the same rim diameter.
Before ordering tires
Read the driver-door tire placard. Match the installed wheel, axle, tire class, load index, speed rating and any OE marking. The size alone cannot approve a replacement SKU. Tire-sidewall maximum pressure is not your vehicle’s cold inflation pressure.
Read the 265/70R17 size page and 275/65R18 size page for separately recorded vehicle applications. Use the calculator for other sizes.
Sources and scope
- BFGoodrich / Michelin North America — 265/70R17 product variants (checked 2026-11-01)
- Goodyear — 2025 Chevrolet Silverado 1500: version/option and tire size (checked 2026-11-01)
- Goodyear — 2025 Ford F-150: version/option and tire size (checked 2026-11-01)
- Goodyear — 2025 GMC Sierra 1500: version/option and tire size (checked 2026-11-01)
- Goodyear — 2025 Toyota Tacoma: version/option and tire size (checked 2026-11-01)
Research checked November 2, 2026. A source-observed size is not final product fitment. Confirm the actual vehicle and current manufacturer guidance.