275/65R18 vs 265/60R18
265/60R18 has an overall diameter of 775.2 mm (30.52") compared with 814.7 mm (32.07") for 275/65R18, a difference of -39.5 mm (-4.85 %). The sidewall changes by -19.7 mm, section width by -10 mm and ride height by -19.7 mm. Using the ETRTO rolling circumference, 275/65R18 turns 402 times per kilometre and 265/60R18 turns 423 times. With 265/60R18 fitted to a car calibrated for 275/65R18, an indicated 100 km/h is a true 95.2 km/h, and the odometer records 105.1 km for every 100 km driven. This exceeds the commonly quoted 3 % tolerance; check clearances, ABS/ESC calibration and local roadworthy rules (VSB 14 in Australia).
Full comparison
| Measurement | 275/65R18 | 265/60R18 | Difference |
|---|---|---|---|
| Section width | 275 mm | 265 mm | -10 mm |
| Sidewall height | 178.8 mm | 159.0 mm | -19.7 mm |
| Rim diameter | 18" | 18" | 0.0" |
| Overall diameter | 814.7 mm (32.07") | 775.2 mm (30.52") | -39.5 mm (-4.85 %) |
| Static circumference | 2559 mm | 2435 mm | -124 mm |
| Rolling circumference (ETRTO) | 2485 mm | 2364 mm | -120 mm |
| Revs per km | 402 | 423 | +21 |
| Ride height | -19.7 mm | ||
| Inch equivalent | 32.1×10.8R18 | 30.5×10.4R18 | |
| Approved rim widths (approx.) | 7.5″–9″ | 7.5″–9″ |
Speedometer error
| Speedo reads | 40 | 50 | 60 | 80 | 100 | 110 |
|---|---|---|---|---|---|---|
| Actual speed (km/h) | 38.1 | 47.6 | 57.1 | 76.1 | 95.2 | 104.7 |
| Error (km/h) | -1.9 | -2.4 | -2.9 | -3.9 | -4.8 | -5.3 |
Assumes the speedo was accurate on 275/65R18. Odometer records 105.1 km for every 100 km actually driven.
- The 265/60R18 is 39.5 mm (4.85 %) smaller in diameter, so your speedo will read high and your odometer will over-record distance.
- Section width changes by -10 mm. Check guard, strut and inner-arch clearance and that the rim width is within the approved range for the new tyre.
- A diameter change over 3 % is outside the usual rule of thumb; check local roadworthy rules (in Australia see VSB 14 / NCOP Section LS) and ABS/ESC calibration.
Is 265/60R18 legal in Australia? Needs certification
| Overall diameter (VSB 14 LS 4.2.4) 265/60R18 is 39.5 mm smaller than 275/65R18; the limit without certification is -26 mm. | Cert. |
| Speedometer (ADR 18/03) A smaller tyre makes the speedo read high: at an indicated 100 km/h you would be doing 95.2 km/h (over-read 4.8 km/h; ADR 18 allows up to 13.5 km/h at that speed). | OK |
| Load index (tyre placard / ADR 42) Enter the placard load index and the replacement tyre load index to check. | ? |
| Speed rating (tyre placard / ADR 42) Enter the placard speed rating and the replacement tyre speed rating to check. | ? |
Frequently asked
Can I fit 265/60R18 instead of 275/65R18?
Overall diameter changes by -39.5 mm (-4.85 %). That is outside the 3 % rule of thumb, so it may rub, upset ABS/ESC calibration and may not be legal without certification. In Australia VSB 14 allows up to +15 mm for passenger cars and +50 mm for 4WDs/goods vehicles without certification.
How much will my speedo be out with 265/60R18?
Your speedo will read high by about 4.85 %. At an indicated 100 km/h you would actually be travelling 95.2 km/h, and at 110 km/h about 104.7 km/h.
What is the rolling circumference of 265/60R18?
Static circumference is 2435 mm; the ETRTO rolling circumference under load is about 2364 mm, which is 423 revolutions per kilometre.
265/60R18 in inches
265/60R18 is approximately 30.5×10.4R18: 30.5" tall, 10.4" wide, on a 18" rim, with a 6.3" sidewall.
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