225/65R17 vs 235/55R19
235/55R19 has an overall diameter of 741.1 mm (29.18") compared with 724.3 mm (28.52") for 225/65R17, a difference of +16.8 mm (+2.32 %). The sidewall changes by -17.0 mm, section width by +10 mm and ride height by +8.4 mm. Using the ETRTO rolling circumference, 225/65R17 turns 453 times per kilometre and 235/55R19 turns 442 times. With 235/55R19 fitted to a car calibrated for 225/65R17, an indicated 100 km/h is a true 102.3 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 | 225/65R17 | 235/55R19 | Difference |
|---|---|---|---|
| Section width | 225 mm | 235 mm | +10 mm |
| Sidewall height | 146.3 mm | 129.3 mm | -17.0 mm |
| Rim diameter | 17" | 19" | +2.0" |
| Overall diameter | 724.3 mm (28.52") | 741.1 mm (29.18") | +16.8 mm (+2.32 %) |
| Static circumference | 2275 mm | 2328 mm | +53 mm |
| Rolling circumference (ETRTO) | 2209 mm | 2260 mm | +51 mm |
| Revs per km | 453 | 442 | -10 |
| Ride height | +8.4 mm | ||
| Inch equivalent | 28.5×8.9R17 | 29.2×9.3R19 | |
| Approved rim widths (approx.) | 6″–7.5″ | 6.5″–8.5″ |
Speedometer error
| Speedo reads | 40 | 50 | 60 | 80 | 100 | 110 |
|---|---|---|---|---|---|---|
| Actual speed (km/h) | 40.9 | 51.2 | 61.4 | 81.9 | 102.3 | 112.6 |
| Error (km/h) | +0.9 | +1.2 | +1.4 | +1.9 | +2.3 | +2.6 |
Assumes the speedo was accurate on 225/65R17. Odometer records 97.7 km for every 100 km actually driven.
- The 235/55R19 is 16.8 mm (2.32 %) 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 17" to 19", so new wheels are required.
Is 235/55R19 legal in Australia? Needs certification
| Overall diameter (VSB 14 LS 4.2.4) 235/55R19 is 16.8 mm larger than 225/65R17; 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 102.3 km/h. ADR 18 requires the speedo never to read below true speed, but factory speedos typically over-read by 2-6 %, so a 2.3 % 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 235/55R19 instead of 225/65R17?
Overall diameter changes by +16.8 mm (+2.32 %). 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 235/55R19?
Your speedo will read low by about 2.32 %. At an indicated 100 km/h you would actually be travelling 102.3 km/h, and at 110 km/h about 112.6 km/h.
What is the rolling circumference of 235/55R19?
Static circumference is 2328 mm; the ETRTO rolling circumference under load is about 2260 mm, which is 442 revolutions per kilometre.
235/55R19 in inches
235/55R19 is approximately 29.2×9.3R19: 29.2" tall, 9.3" wide, on a 19" rim, with a 5.1" sidewall.
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