265/60R18 vs 275/70R16
275/70R16 has an overall diameter of 791.4 mm (31.16") compared with 775.2 mm (30.52") for 265/60R18, a difference of +16.2 mm (+2.09 %). The sidewall changes by +33.5 mm, section width by +10 mm and ride height by +8.1 mm. Using the ETRTO rolling circumference, 265/60R18 turns 423 times per kilometre and 275/70R16 turns 414 times. With 275/70R16 fitted to a car calibrated for 265/60R18, an indicated 100 km/h is a true 102.1 km/h, and the odometer records 98 km for every 100 km driven. This is close to the commonly quoted 3 % tolerance, so check clearance and local rules.
Full comparison
| Measurement | 265/60R18 | 275/70R16 | Difference |
|---|---|---|---|
| Section width | 265 mm | 275 mm | +10 mm |
| Sidewall height | 159.0 mm | 192.5 mm | +33.5 mm |
| Rim diameter | 18" | 16" | -2.0" |
| Overall diameter | 775.2 mm (30.52") | 791.4 mm (31.16") | +16.2 mm (+2.09 %) |
| Static circumference | 2435 mm | 2486 mm | +51 mm |
| Rolling circumference (ETRTO) | 2364 mm | 2414 mm | +49 mm |
| Revs per km | 423 | 414 | -9 |
| Ride height | +8.1 mm | ||
| Inch equivalent | 30.5×10.4R18 | 31.2×10.8R16 | |
| Approved rim widths (approx.) | 7.5″–9″ | 7.5″–9″ |
Speedometer error
| Speedo reads | 40 | 50 | 60 | 80 | 100 | 110 |
|---|---|---|---|---|---|---|
| Actual speed (km/h) | 40.8 | 51.0 | 61.3 | 81.7 | 102.1 | 112.3 |
| Error (km/h) | +0.8 | +1.0 | +1.3 | +1.7 | +2.1 | +2.3 |
Assumes the speedo was accurate on 265/60R18. Odometer records 98.0 km for every 100 km actually driven.
- The 275/70R16 is 16.2 mm (2.09 %) larger in diameter, so your speedo will read low and your odometer will under-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.
- Rim diameter changes from 18" to 16", so new wheels are required.
Is 275/70R16 legal in Australia? Needs certification
| Overall diameter (VSB 14 LS 4.2.4) 275/70R16 is 16.2 mm larger than 265/60R18; 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 102.1 km/h. ADR 18 requires the speedo never to read below true speed, but factory speedos typically over-read by 2-6 %, so a 2.1 % 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 275/70R16 instead of 265/60R18?
Overall diameter changes by +16.2 mm (+2.09 %). 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 275/70R16?
Your speedo will read low by about 2.09 %. At an indicated 100 km/h you would actually be travelling 102.1 km/h, and at 110 km/h about 112.3 km/h.
What is the rolling circumference of 275/70R16?
Static circumference is 2486 mm; the ETRTO rolling circumference under load is about 2414 mm, which is 414 revolutions per kilometre.
275/70R16 in inches
275/70R16 is approximately 31.2×10.8R16: 31.2" tall, 10.8" wide, on a 16" rim, with a 7.6" sidewall.
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