17-inch rim · tyre size comparison
205/50 R17 vs 225/45 R17
225/45 R17 is 2.5 mm (0.1 in) shorter than 205/50 R17, a -0.39% difference in overall diameter. That is well inside the ±3% limit commonly used to screen a tire size change; it is a nominal calculation, not a fitment approval.
- Diameter difference
- -2.5 mm
- -0.1 in · -0.39%
- Indicated 70 mph
- 69.7 mph
- Actual speed on 225/45 R17, if the speedometer was accurate on 205/50 R17.
- Sidewall height
- -1.25 mm
- 102.5 mm to 101.25 mm.
Dimensions side by side
| Measurement | 205/50 R17 | 225/45 R17 | Difference |
|---|---|---|---|
| Overall diameter | 636.8 mm25.07 in | 634.3 mm24.97 in | -2.5 mm (-0.39%)-0.1 in |
| Section width | 205 mm8.07 in | 225 mm8.86 in | +20 mm+0.79 in |
| Sidewall height | 102.5 mm4.04 in | 101.25 mm3.99 in | -1.25 mm-0.05 in |
| Circumference | 2,000.57 mm78.76 in | 1,992.71 mm78.45 in | -7.85 mm-0.31 in |
| Rim diameter | 431.8 mm17 in | 431.8 mm17 in | 0 mm0 in |
| Revolutions per mile | 804.44 | 807.61 | +3.17 |
| Revolutions per km | 499.86 | 501.83 | +1.97 |
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 225/45 R17
If the speedometer was accurate on 205/50 R17, fitting 225/45 R17 means the car is travelling 0.39% slower than it shows, and the odometer over-records distance by about the same amount.
| Speedometer shows | Actual on 225/45 R17 | Difference |
|---|---|---|
| 30 mph | 29.88 mph | -0.12 mph |
| 50 mph | 49.8 mph | -0.2 mph |
| 60 mph | 59.76 mph | -0.24 mph |
| 70 mph | 69.73 mph | -0.27 mph |
| 50 km/h | 49.8 km/h | -0.2 km/h |
| 100 km/h | 99.61 km/h | -0.39 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 205/50 R17 to 225/45 R17
Wheels
Both fit 17-inch wheels. Our rim-width starting estimate is 6 to 7 inches for 205/50 R17 and 7 to 8 inches for 225/45 R17, so a 7-inch wheel sits in both ranges. The exact tyre's approved rim range takes priority.
Sidewall and ride comfort
Sidewall height differs by only 1.25 mm (102.5 vs 101.25 mm), so ride comfort and steering feel will depend more on the tyre model and pressures than on the size.
Contact width
225/45 R17 is 20 mm wider in nominal section width (9.8%). 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 -1.3 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
Effective gearing changes by +0.39%, too little to notice from the driver's seat.
ABS, stability control and AWD
These systems compare wheel speeds. Fit the same size on both ends of an axle, 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.
205/50 R17
225/45 R17
- Audi A3 8V (2012–2020)Factory trim
- Audi TT 8N (Mk1) (1998–2006)Factory and popular setup
- BMW 1 Series E81/E82/E87/E88 (2004–2013)Factory trim
- BMW 3 Series E90 / E92 (2005–2013)Factory trim
- Honda Civic Type R EP3 (2001–2005)Popular setup
- Honda Civic Type R FN2 (2007–2011)Popular setup
- Lexus IS XE30 (2013–present)Factory trim
- Mazda RX-7 FC3S / FC3C (1985–1992)Popular setup
- MINI Cooper S / John Cooper Works F56 (2014–2024)Popular setup
- Mitsubishi Lancer Evolution VI (CP9A), incl. Tommi Makinen Edition (1999–2001)Factory trim
- Nissan Silvia S14 (1993–1998)Popular setup
- Renault Clio Renaultsport 197 / 200 Mk3 (2006–2012)Popular setup
- SEAT / Cupra Leon Mk4 (KL) (2020–present)Factory trim
- Subaru BRZ ZD8 (2022–present)Popular setup
- Subaru Impreza WRX STI GD (2000–2007)Factory and popular setup
- Toyota Auris E180, 2nd gen (2012–2018)Factory trim
- Toyota GR86 ZN8 (2022–present)Popular setup
- Toyota GT86 / 86 ZN6 (2012–2021)Popular setup
- Volkswagen Golf GTI Mk5 (2004–2009)Factory trim
- Volkswagen Golf GTI Mk7 (2013–2020)Factory trim
- Volkswagen Golf GTI Mk8 (2020–present)Factory trim
- Volkswagen Golf Mk4 (1997–2004)Factory and popular setup
- Volkswagen Jetta / GLI Mk6 (A6) (2011–2018)Factory trim
More comparisons
Questions
Can I use 225/45 R17 instead of 205/50 R17?
Both fit 17-inch wheels. The diameter difference is -0.39%, well 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 225/45 R17 than 205/50 R17?
Overall diameter is 2.5 mm (0.1 in) smaller: 634.3 vs 636.8 mm. Section width is 20 mm wider, and the sidewall is 1.25 mm shorter. These are nominal figures; real tyres vary by model and rim width.
Will 225/45 R17 change my speedometer reading?
Yes, by 0.39%. If the speedometer was accurate on 205/50 R17, an indicated 60 mph would be about 59.8 mph on 225/45 R17, and an indicated 100 km/h about 99.6 km/h. You would be going slower than the speedometer shows.
Which is better, 205/50 R17 or 225/45 R17?
Neither in general. 225/45 R17 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.