205/55R16 vs 215/50R17
215/50R17 has an overall diameter of 646.8 mm (25.46") compared with 631.9 mm (24.88") for 205/55R16, a difference of +14.9 mm (+2.36 %). The sidewall changes by -5.2 mm, section width by +10 mm and ride height by +7.4 mm. Using the ETRTO rolling circumference, 205/55R16 turns 519 times per kilometre and 215/50R17 turns 507 times. With 215/50R17 fitted to a car calibrated for 205/55R16, an indicated 100 km/h is a true 102.4 km/h, and the odometer records 97.7 km for every 100 km driven. This is close to the commonly quoted 3 % tolerance, so check clearance and local rules.
Full comparison
| Measurement | 205/55R16 | 215/50R17 | Difference |
|---|---|---|---|
| Section width | 205 mm | 215 mm | +10 mm |
| Sidewall height | 112.8 mm | 107.5 mm | -5.2 mm |
| Rim diameter | 16" | 17" | +1.0" |
| Overall diameter | 631.9 mm (24.88") | 646.8 mm (25.46") | +14.9 mm (+2.36 %) |
| Static circumference | 1985 mm | 2032 mm | +47 mm |
| Rolling circumference (ETRTO) | 1927 mm | 1973 mm | +45 mm |
| Revs per km | 519 | 507 | -12 |
| Ride height | +7.4 mm | ||
| Inch equivalent | 24.9×8.1R16 | 25.5×8.5R17 | |
| Approved rim widths (approx.) | 5.5″–7.5″ | 6″–8″ |
Speedometer error
| Speedo reads | 40 | 50 | 60 | 80 | 100 | 110 |
|---|---|---|---|---|---|---|
| Actual speed (km/h) | 40.9 | 51.2 | 61.4 | 81.9 | 102.4 | 112.6 |
| Error (km/h) | +0.9 | +1.2 | +1.4 | +1.9 | +2.4 | +2.6 |
Assumes the speedo was accurate on 205/55R16. Odometer records 97.7 km for every 100 km actually driven.
- The 215/50R17 is 14.9 mm (2.36 %) 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 16" to 17", so new wheels are required.
Is 215/50R17 legal in Australia? Within limits, verify speedo
| Overall diameter (VSB 14 LS 4.2.4) Diameter change of +14.9 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 larger tyre makes the speedo read lower: at an indicated 100 km/h you would be doing 102.4 km/h. ADR 18 requires the speedo never to read below true speed, but factory speedos typically over-read by 2-6 %, so a 2.4 % 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 215/50R17 instead of 205/55R16?
Overall diameter changes by +14.9 mm (+2.36 %). 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 215/50R17?
Your speedo will read low by about 2.36 %. At an indicated 100 km/h you would actually be travelling 102.4 km/h, and at 110 km/h about 112.6 km/h.
What is the rolling circumference of 215/50R17?
Static circumference is 2032 mm; the ETRTO rolling circumference under load is about 1973 mm, which is 507 revolutions per kilometre.
215/50R17 in inches
215/50R17 is approximately 25.5×8.5R17: 25.5" tall, 8.5" wide, on a 17" rim, with a 4.2" sidewall.
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