245/45R17 vs 215/55R17
215/55R17 has an overall diameter of 668.3 mm (26.31") compared with 652.3 mm (25.68") for 245/45R17, a difference of +16.0 mm (+2.45 %). The sidewall changes by +8.0 mm, section width by -30 mm and ride height by +8.0 mm. Using the ETRTO rolling circumference, 245/45R17 turns 503 times per kilometre and 215/55R17 turns 491 times. With 215/55R17 fitted to a car calibrated for 245/45R17, an indicated 100 km/h is a true 102.5 km/h, and the odometer records 97.6 km for every 100 km driven. This is close to the commonly quoted 3 % tolerance, so check clearance and local rules.
Full comparison
| Measurement | 245/45R17 | 215/55R17 | Difference |
|---|---|---|---|
| Section width | 245 mm | 215 mm | -30 mm |
| Sidewall height | 110.3 mm | 118.3 mm | +8.0 mm |
| Rim diameter | 17" | 17" | 0.0" |
| Overall diameter | 652.3 mm (25.68") | 668.3 mm (26.31") | +16.0 mm (+2.45 %) |
| Static circumference | 2049 mm | 2100 mm | +50 mm |
| Rolling circumference (ETRTO) | 1990 mm | 2038 mm | +49 mm |
| Revs per km | 503 | 491 | -12 |
| Ride height | +8.0 mm | ||
| Inch equivalent | 25.7×9.6R17 | 26.3×8.5R17 | |
| Approved rim widths (approx.) | 7.5″–9″ | 6″–8″ |
Speedometer error
| Speedo reads | 40 | 50 | 60 | 80 | 100 | 110 |
|---|---|---|---|---|---|---|
| Actual speed (km/h) | 41.0 | 51.2 | 61.5 | 82.0 | 102.5 | 112.7 |
| Error (km/h) | +1.0 | +1.2 | +1.5 | +2.0 | +2.5 | +2.7 |
Assumes the speedo was accurate on 245/45R17. Odometer records 97.6 km for every 100 km actually driven.
- The 215/55R17 is 16 mm (2.45 %) larger in diameter, so your speedo will read low and your odometer will under-record distance.
- Section width changes by -30 mm. Check guard, strut and inner-arch clearance and that the rim width is within the approved range for the new tyre.
Is 215/55R17 legal in Australia? Needs certification
| Overall diameter (VSB 14 LS 4.2.4) 215/55R17 is 16.0 mm larger than 245/45R17; 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 102.5 km/h. ADR 18 requires the speedo never to read below true speed, but factory speedos typically over-read by 2-6 %, so a 2.5 % 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 215/55R17 instead of 245/45R17?
Overall diameter changes by +16.0 mm (+2.45 %). 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 215/55R17?
Your speedo will read low by about 2.45 %. At an indicated 100 km/h you would actually be travelling 102.5 km/h, and at 110 km/h about 112.7 km/h.
What is the rolling circumference of 215/55R17?
Static circumference is 2100 mm; the ETRTO rolling circumference under load is about 2038 mm, which is 491 revolutions per kilometre.
215/55R17 in inches
215/55R17 is approximately 26.3×8.5R17: 26.3" tall, 8.5" wide, on a 17" rim, with a 4.7" sidewall.
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