285/70R17 vs 265/65R17
265/65R17 has an overall diameter of 776.3 mm (30.56") compared with 830.8 mm (32.71") for 285/70R17, a difference of -54.5 mm (-6.56 %). The sidewall changes by -27.2 mm, section width by -20 mm and ride height by -27.2 mm. Using the ETRTO rolling circumference, 285/70R17 turns 395 times per kilometre and 265/65R17 turns 422 times. With 265/65R17 fitted to a car calibrated for 285/70R17, an indicated 100 km/h is a true 93.4 km/h, and the odometer records 107 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 | 285/70R17 | 265/65R17 | Difference |
|---|---|---|---|
| Section width | 285 mm | 265 mm | -20 mm |
| Sidewall height | 199.5 mm | 172.3 mm | -27.2 mm |
| Rim diameter | 17" | 17" | 0.0" |
| Overall diameter | 830.8 mm (32.71") | 776.3 mm (30.56") | -54.5 mm (-6.56 %) |
| Static circumference | 2610 mm | 2439 mm | -171 mm |
| Rolling circumference (ETRTO) | 2534 mm | 2368 mm | -166 mm |
| Revs per km | 395 | 422 | +28 |
| Ride height | -27.2 mm | ||
| Inch equivalent | 32.7×11.2R17 | 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) | 37.4 | 46.7 | 56.1 | 74.8 | 93.4 | 102.8 |
| Error (km/h) | -2.6 | -3.3 | -3.9 | -5.2 | -6.6 | -7.2 |
Assumes the speedo was accurate on 285/70R17. Odometer records 107.0 km for every 100 km actually driven.
- The 265/65R17 is 54.5 mm (6.56 %) 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.
- 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 265/65R17 legal in Australia? Needs certification
| Overall diameter (VSB 14 LS 4.2.4) 265/65R17 is 54.5 mm smaller than 285/70R17; 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 93.4 km/h (over-read 6.6 km/h; ADR 18 allows up to 13.3 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 285/70R17?
Overall diameter changes by -54.5 mm (-6.56 %). 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 265/65R17?
Your speedo will read high by about 6.56 %. At an indicated 100 km/h you would actually be travelling 93.4 km/h, and at 110 km/h about 102.8 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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