295/40R21 vs 275/55R19
275/55R19 has an overall diameter of 785.1 mm (30.91") compared with 769.4 mm (30.29") for 295/40R21, a difference of +15.7 mm (+2.04 %). The sidewall changes by +33.3 mm, section width by -20 mm and ride height by +7.8 mm. Using the ETRTO rolling circumference, 295/40R21 turns 426 times per kilometre and 275/55R19 turns 418 times. With 275/55R19 fitted to a car calibrated for 295/40R21, an indicated 100 km/h is a true 102 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 | 295/40R21 | 275/55R19 | Difference |
|---|---|---|---|
| Section width | 295 mm | 275 mm | -20 mm |
| Sidewall height | 118.0 mm | 151.3 mm | +33.3 mm |
| Rim diameter | 21" | 19" | -2.0" |
| Overall diameter | 769.4 mm (30.29") | 785.1 mm (30.91") | +15.7 mm (+2.04 %) |
| Static circumference | 2417 mm | 2466 mm | +49 mm |
| Rolling circumference (ETRTO) | 2347 mm | 2395 mm | +48 mm |
| Revs per km | 426 | 418 | -9 |
| Ride height | +7.8 mm | ||
| Inch equivalent | 30.3×11.6R21 | 30.9×10.8R19 | |
| Approved rim widths (approx.) | 10″–11.5″ | 7.5″–9.5″ |
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 295/40R21. Odometer records 98.0 km for every 100 km actually driven.
- The 275/55R19 is 15.7 mm (2.04 %) larger in diameter, so your speedo will read low and your odometer will under-record distance.
- Section width changes by -20 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 21" to 19", so new wheels are required.
Is 275/55R19 legal in Australia? Needs certification
| Overall diameter (VSB 14 LS 4.2.4) 275/55R19 is 15.7 mm larger than 295/40R21; 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 275/55R19 instead of 295/40R21?
Overall diameter changes by +15.7 mm (+2.04 %). 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 275/55R19?
Your speedo will read low by about 2.04 %. 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 275/55R19?
Static circumference is 2466 mm; the ETRTO rolling circumference under load is about 2395 mm, which is 418 revolutions per kilometre.
275/55R19 in inches
275/55R19 is approximately 30.9×10.8R19: 30.9" tall, 10.8" wide, on a 19" rim, with a 6.0" sidewall.
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