31×10.5R15 vs 265/70R17
265/70R17 has an overall diameter of 802.8 mm (31.61") compared with 787.4 mm (31.00") for 31×10.5R15, a difference of +15.4 mm (+1.96 %). The sidewall changes by -17.7 mm, section width by -2 mm and ride height by +7.7 mm. Using the ETRTO rolling circumference, 31×10.5R15 turns 416 times per kilometre and 265/70R17 turns 408 times. With 265/70R17 fitted to a car calibrated for 31×10.5R15, an indicated 100 km/h is a true 102 km/h, and the odometer records 98.1 km for every 100 km driven. This is within the commonly quoted 3 % tolerance.
Full comparison
| Measurement | 31×10.5R15 | 265/70R17 | Difference |
|---|---|---|---|
| Section width | 267 mm | 265 mm | -2 mm |
| Sidewall height | 203.2 mm | 185.5 mm | -17.7 mm |
| Rim diameter | 15" | 17" | +2.0" |
| Overall diameter | 787.4 mm (31.00") | 802.8 mm (31.61") | +15.4 mm (+1.96 %) |
| Static circumference | 2474 mm | 2522 mm | +48 mm |
| Rolling circumference (ETRTO) | 2402 mm | 2449 mm | +47 mm |
| Revs per km | 416 | 408 | -8 |
| Ride height | +7.7 mm | ||
| Inch equivalent | 31×10.5R15 | 31.6×10.4R17 | |
| Approved rim widths (approx.) | 7″–8.5″ | 7.5″–9″ |
Speedometer error
| Speedo reads | 40 | 50 | 60 | 80 | 100 | 110 |
|---|---|---|---|---|---|---|
| Actual speed (km/h) | 40.8 | 51.0 | 61.2 | 81.6 | 102.0 | 112.2 |
| Error (km/h) | +0.8 | +1.0 | +1.2 | +1.6 | +2.0 | +2.2 |
Assumes the speedo was accurate on 31×10.5R15. Odometer records 98.1 km for every 100 km actually driven.
- The 265/70R17 is 15.4 mm (1.96 %) larger in diameter, so your speedo will read low and your odometer will under-record distance.
- Section width changes by -2 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 15" to 17", so new wheels are required.
Is 265/70R17 legal in Australia? Needs certification
| Overall diameter (VSB 14 LS 4.2.4) 265/70R17 is 15.4 mm larger than 31×10.5R15; the limit without certification for a passenger car (MA/MB) is +15 mm. Larger increases need an approved signatory / engineering certificate (modification code LS or state equivalent) and may not be permitted at all. | Cert. |
| Speedometer (ADR 18/03) A larger tyre makes the speedo read lower: at an indicated 100 km/h you would be doing 102.0 km/h. ADR 18 requires the speedo never to read below true speed, but factory speedos typically over-read by 2-6 %, so a 2.0 % increase is usually absorbed. Verify with a GPS speed app after fitting. | Verify |
| 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 265/70R17 instead of 31×10.5R15?
Overall diameter changes by +15.4 mm (+1.96 %). That is within the usual 3 % rule of thumb, so it is generally an acceptable swap provided the load index and speed rating meet your tyre placard and the tyre suits your rim width. 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 265/70R17?
Your speedo will read low by about 1.96 %. At an indicated 100 km/h you would actually be travelling 102 km/h, and at 110 km/h about 112.2 km/h.
What is the rolling circumference of 265/70R17?
Static circumference is 2522 mm; the ETRTO rolling circumference under load is about 2449 mm, which is 408 revolutions per kilometre.
265/70R17 in inches
265/70R17 is approximately 31.6×10.4R17: 31.6" tall, 10.4" wide, on a 17" rim, with a 7.3" sidewall.
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