19-inch rim · tyre size comparison
235/35 R19 vs 255/30 R19
255/30 R19 is 11.5 mm (0.45 in) shorter than 235/35 R19, a -1.78% difference in overall diameter. That is inside the ±3% limit commonly used to screen a tire size change; it is a nominal calculation, not a fitment approval.
- Diameter difference
- -11.5 mm
- -0.45 in · -1.78%
- Indicated 70 mph
- 68.8 mph
- Actual speed on 255/30 R19, if the speedometer was accurate on 235/35 R19.
- Sidewall height
- -5.75 mm
- 82.25 mm to 76.5 mm.
Dimensions side by side
| Measurement | 235/35 R19 | 255/30 R19 | Difference |
|---|---|---|---|
| Overall diameter | 647.1 mm25.48 in | 635.6 mm25.02 in | -11.5 mm (-1.78%)-0.45 in |
| Section width | 235 mm9.25 in | 255 mm10.04 in | +20 mm+0.79 in |
| Sidewall height | 82.25 mm3.24 in | 76.5 mm3.01 in | -5.75 mm-0.23 in |
| Circumference | 2,032.92 mm80.04 in | 1,996.8 mm78.61 in | -36.13 mm-1.42 in |
| Rim diameter | 482.6 mm19 in | 482.6 mm19 in | 0 mm0 in |
| Revolutions per mile | 791.64 | 805.96 | +14.32 |
| Revolutions per km | 491.9 | 500.8 | +8.9 |
Calculated from the nominal size codes, without load or tread wear. Real tyres vary by model, rim width and pressure, so the exact tyre's published dimensions take priority.
Speedometer with 255/30 R19
If the speedometer was accurate on 235/35 R19, fitting 255/30 R19 means the car is travelling 1.78% slower than it shows, and the odometer over-records distance by about the same amount.
| Speedometer shows | Actual on 255/30 R19 | Difference |
|---|---|---|
| 30 mph | 29.47 mph | -0.53 mph |
| 50 mph | 49.11 mph | -0.89 mph |
| 60 mph | 58.93 mph | -1.07 mph |
| 70 mph | 68.76 mph | -1.24 mph |
| 50 km/h | 49.11 km/h | -0.89 km/h |
| 100 km/h | 98.22 km/h | -1.78 km/h |
UN ECE Regulation 39, used in the UK and EU, does not allow a speedometer to show less than the true speed, so many read slightly high from the factory. A shorter tyre adds to it. Calibration varies by car; these figures are the tyre-size effect only.
What changes from 235/35 R19 to 255/30 R19
Wheels
Both fit 19-inch wheels. Our rim-width starting estimate is 7.5 to 8.5 inches for 235/35 R19 and 8 to 9 inches for 255/30 R19, so a 8 to 8.5-inch wheel sits in both ranges. The exact tyre's approved rim range takes priority.
Sidewall and ride comfort
255/30 R19 has 5.75 mm less sidewall (76.5 vs 82.25 mm). A shorter sidewall usually sharpens steering response, but rides a little firmer and leaves the rim more exposed to potholes and kerbs.
Contact width
255/30 R19 is 20 mm wider in nominal section width (8.5%). A wider tyre usually puts a wider, shorter contact patch on the road, which can help dry grip, but it may follow ruts more, clear standing water less readily and add some rolling resistance.
Wheel well clearance
Ride height changes by about -5.8 mm, and the top of the tyre moves the same distance away from the arch. On the same wheel width and offset, each sidewall moves about 10 mm further out towards the arch lip and further in towards the suspension. Check clearance at full steering lock and full suspension compression, especially on a lowered car.
Gearing
The effective final drive changes by +1.81%: 3,000 rpm at a given road speed becomes about 3,050 rpm. Gearing gets slightly shorter, so acceleration in each gear sharpens and cruising revs rise.
ABS, stability control and AWD
These systems compare wheel speeds. Fit the same size on both ends of an axle; with a 1.8% diameter gap, never mix 235/35 R19 and 255/30 R19 on an AWD car, and follow the car maker's rolling-circumference limits, which can be much tighter than 3%.
General tendencies from the nominal numbers, not a test of any tyre. Load index, speed rating, tyre construction and the car's approved sizes matter more than these rules of thumb.
Explained in our guides
- Plus-sizing wheels: tyre diameter and speedometer changesWork through a 17 to 18 inch wheel change, compare tyre diameters and speedometer effects, and understand why a 3% rule cannot approve fitment.
- Staggered vs square wheels: tyres, rotation and AWDCompare square and staggered wheel setups, calculate front-to-rear tyre diameter, and understand rotation limits and all-wheel-drive requirements.
- How to read a tyre size, load index and sidewall markingsDecode tyre width, aspect ratio, rim diameter, load and speed markings, then calculate sidewall height and diameter using a 225/45 R17 example.
Cars in our guides using these sizes
Factory trims and popular community setups from our fitment guides. A popular setup is not a factory approval; each guide explains its trims, axles and clearance limits.
235/35 R19
- Audi RS3 8V (2015–2020)Factory trim
- Audi S3 8V (2013–2020)Factory trim
- Audi S3 8Y (2020–present)Factory trim
- BMW M3 E46 (2000–2006)Factory trim
- Ford Focus RS Mk2, incl. RS500 (2009–2011)Factory and popular setup
- Ford Focus RS Mk3 (2016–2018)Factory trim
- Ford Focus ST / RS Mk2 (2005–2010)Factory and popular setup
- Ford Focus ST Mk3 (2012–2018)Factory and popular setup
- Hyundai i30 N PDe (2017–present)Factory and popular setup
- Hyundai Veloster N JS (2018–2022)Factory and popular setup
- Infiniti G35 Coupe V35 (2003–2007)Popular setup
- Mazda Mazda3 BP (2019–present)Popular setup
- Mercedes-AMG CLA45 C117 / X117 (2013–2019)Factory and popular setup
- Mercedes-Benz A-Class W177 (2018–present)Factory and popular setup
- Mercedes-Benz A45 AMG W176 (2013–2018)Factory and popular setup
- Mercedes-Benz C63 AMG W204 / C204 (2008–2014)Factory and popular setup
- Porsche 911 997 (2004–2012)Factory and popular setup
- Renault Mégane RS Mk3 (2010–2016)Factory trim
- SEAT / Cupra Leon Mk4 (KL) (2020–present)Factory and popular setup
- SEAT Leon Cupra Mk3 / 5F (2014–2020)Factory trim
- Vauxhall / Opel Astra VXR / Astra OPC H (2005–2010)Factory trim
- Volkswagen Golf GTI Mk7 (2013–2020)Factory trim
- Volkswagen Golf GTI Mk8 (2020–present)Factory trim
- Volkswagen Golf R Mk7 (2014–2020)Factory trim
- Volkswagen Golf R Mk8 (2021–present)Factory trim
- Volkswagen Jetta / GLI Mk6 (A6) (2011–2018)Popular setup
- Volkswagen Scirocco R Mk3 (2009–2017)Factory and popular setup
255/30 R19
- Audi RS3 8V (2015–2020)Factory trim
- Mercedes-Benz C63 AMG W204 / C204 (2008–2014)Factory and popular setup
More comparisons
Questions
Can I use 255/30 R19 instead of 235/35 R19?
Both fit 19-inch wheels. The diameter difference is -1.78%, inside the ±3% screening limit. That does not approve fitment: check the car maker's approved sizes, load index, speed rating, rim width and clearance first.
How much bigger is 255/30 R19 than 235/35 R19?
Overall diameter is 11.5 mm (0.45 in) smaller: 635.6 vs 647.1 mm. Section width is 20 mm wider, and the sidewall is 5.75 mm shorter. These are nominal figures; real tyres vary by model and rim width.
Will 255/30 R19 change my speedometer reading?
Yes, by 1.78%. If the speedometer was accurate on 235/35 R19, an indicated 60 mph would be about 58.9 mph on 255/30 R19, and an indicated 100 km/h about 98.2 km/h. You would be going slower than the speedometer shows.
Which is better, 235/35 R19 or 255/30 R19?
Neither in general. 235/35 R19 has the taller sidewall, which usually rides more comfortably; 255/30 R19 usually steers more sharply. 255/30 R19 is wider, which can help dry grip; the narrower size is usually better in standing water and snow. The size listed for your car's trim, on its placard or in the handbook, is the safe default.
Check the exact tyre
Size codes give nominal dimensions. Before buying, confirm the size is approved for your car and check the exact tyre's load and speed ratings and published dimensions.