285/60R18 vs 265/65R17
265/65R17 has an overall diameter of 776.3 mm (30.56") compared with 799.2 mm (31.46") for 285/60R18, a difference of -22.9 mm (-2.87 %). The sidewall changes by +1.3 mm, section width by -20 mm and ride height by -11.5 mm. Using the ETRTO rolling circumference, 285/60R18 turns 410 times per kilometre and 265/65R17 turns 422 times. With 265/65R17 fitted to a car calibrated for 285/60R18, an indicated 100 km/h is a true 97.1 km/h, and the odometer records 102.9 km for every 100 km driven. This is close to the commonly quoted 3 % tolerance, so check clearance and local rules.
Full comparison
| Measurement | 285/60R18 | 265/65R17 | Difference |
|---|---|---|---|
| Section width | 285 mm | 265 mm | -20 mm |
| Sidewall height | 171.0 mm | 172.3 mm | +1.3 mm |
| Rim diameter | 18" | 17" | -1.0" |
| Overall diameter | 799.2 mm (31.46") | 776.3 mm (30.56") | -22.9 mm (-2.87 %) |
| Static circumference | 2511 mm | 2439 mm | -72 mm |
| Rolling circumference (ETRTO) | 2438 mm | 2368 mm | -70 mm |
| Revs per km | 410 | 422 | +12 |
| Ride height | -11.5 mm | ||
| Inch equivalent | 31.5×11.2R18 | 30.6×10.4R17 | |
| Approved rim widths (approx.) | 8″–9.5″ | 7.5″–9″ |
Speedometer error
| Speedo reads | 40 | 50 | 60 | 80 | 100 | 110 |
|---|---|---|---|---|---|---|
| Actual speed (km/h) | 38.9 | 48.6 | 58.3 | 77.7 | 97.1 | 106.8 |
| Error (km/h) | -1.1 | -1.4 | -1.7 | -2.3 | -2.9 | -3.2 |
Assumes the speedo was accurate on 285/60R18. Odometer records 102.9 km for every 100 km actually driven.
- The 265/65R17 is 22.9 mm (2.87 %) smaller in diameter, so your speedo will read high and your odometer will over-record distance.
- Section width changes by -20 mm. Check guard, strut and inner-arch clearance and that the rim width is within the approved range for the new tyre.
- Rim diameter changes from 18" to 17", so new wheels are required.
Is 265/65R17 legal in Australia? More info needed
| Overall diameter (VSB 14 LS 4.2.4) Diameter change of -22.9 mm is within the +15 mm / -26 mm allowance for a passenger car (MA/MB) (measured against the largest size the manufacturer designates for the model). | OK |
| Speedometer (ADR 18/03) A smaller tyre makes the speedo read high: at an indicated 100 km/h you would be doing 97.1 km/h (over-read 2.9 km/h; ADR 18 allows up to 13.7 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 265/65R17 instead of 285/60R18?
Overall diameter changes by -22.9 mm (-2.87 %). That is close to the 3 % rule of thumb; it may fit, but check guard, strut and brake clearance and your local rules. 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 265/65R17?
Your speedo will read high by about 2.87 %. At an indicated 100 km/h you would actually be travelling 97.1 km/h, and at 110 km/h about 106.8 km/h.
What is the rolling circumference of 265/65R17?
Static circumference is 2439 mm; the ETRTO rolling circumference under load is about 2368 mm, which is 422 revolutions per kilometre.
265/65R17 in inches
265/65R17 is approximately 30.6×10.4R17: 30.6" tall, 10.4" wide, on a 17" rim, with a 6.8" sidewall.
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