215/45R18 vs 265/40R18
265/40R18 is taller than 215/45R18 by 2.84% — a diameter difference of 0.73″.
What changes between 215/45R18 and 265/40R18
Switching from 215/45R18 to 265/40R18 changes overall diameter by +2.84%, a taller tire by 0.73 inches. This lands inside the ±3% fitment safe zone, so most vehicles will accept the swap without rubbing, speedometer recalibration, or ABS/TPMS complications. Section width moves by +1.97″ (215mm → 265mm), which affects contact patch and fender-well clearance. Sidewall height shifts by +0.36″: a taller sidewall softens ride quality and adds off-road bump protection, with some loss of steering crispness. Revs per mile moves by -22, which translates directly to speedometer error — at an indicated 65 mph, actual speed becomes 66.8 mph. Both sizes share the same 18″ rim, so no wheel change is required — this is a pure tire-only swap.
| Spec | 215/45R18 | 265/40R18 |
|---|---|---|
| Overall diameter | 25.62″ | 26.35″ |
| Section width | 8.46″ (215 mm) | 10.43″ (265 mm) |
| Sidewall height | 3.81″ (45%) | 4.17″ (40%) |
| Rim diameter | 18″ | 18″ |
| Circumference | 80.48″ | 82.77″ |
| Revs per mile | 787 | 765 |
Interactive comparison
275/65R18 or "33" for inch aliases215/45R18
- Diameter
- 25.62″ / 650.7mm
- Section Width
- 8.46″
- Sidewall
- 3.81″ / 96.75mm
- Circumference
- 80.48″
- Revs/Mile
- 787
265/40R18
- Diameter
- 26.35″ / 669.2mm
- Section Width
- 10.43″
- Sidewall
- 4.17″ / 106mm
- Circumference
- 82.77″
- Revs/Mile
- 765
Speedometer & Diameter Impact
Wider tire — verify wheel widthAt an indicated 60 mph, your actual speed is 61.71 mph (99.31 km/h). Your speedometer reads 2.84% low versus actual speed.