Quick Answer
- BMW publishes no tolerance percentage for xDrive. BMW Australia's tyre FAQ says that on xDrive models all four tyres should have as similar a rolling circumference as possible.
- BMW's own xDrive pairs differ front to rear by 0.07% to 0.72% (calculated). The M3 and M4 on 275/35R19 front and 285/30R20 rear are 26.58 in and 26.73 in, a 0.58% gap.
- The calculator compares your pair with that factory range and says whether it is within it or above it. It does not give a safety rating.
Compare front and rear tire sizes for BMW xDrive, with rolling diameter, revs per mile, and and how the gap compares with BMW factory pairs.
Front tire size
You can fill either the size code or the explicit width/aspect/rim fields. The calculator will use whichever is complete.
Front tire metrics
| Size used | 275 / 35 R 19" |
| Sidewall height | 96.25 mm |
| Overall diameter | 675.10 mm (26.58") |
| Circumference | 2120.89 mm (83.50") |
| Revs per km | 471.50 |
| Revs per mile | 758.81 |
| Free radius | 337.55 mm |
| Static loaded radius (est.) | 314.39 mm |
| Rolling radius (est.) | 328.44 mm |
Rear tire metrics
| Size used | 285 / 30 R 20" |
| Sidewall height | 85.50 mm |
| Overall diameter | 679.00 mm (26.73") |
| Circumference | 2133.14 mm (83.98") |
| Revs per km | 468.79 |
| Revs per mile | 754.45 |
| Free radius | 339.50 mm |
| Static loaded radius (est.) | 316.21 mm |
| Rolling radius (est.) | 330.33 mm |
xDrive rolling diameter difference
Based on dynamic rolling diameter. The goal for BMW xDrive is BMW publishes no percentage; the result is compared with the factory pairs BMW lists.
Percent difference in rolling diameter
0.578%
Absolute difference: 3.79 mm (0.15")
Revs per mile difference
4.36 rev/mile
The difference in wheel turns per mile between the two axles (calculated).
Gap on a 0 to 3% scale
This front to rear gap is no larger than the largest gap among the factory xDrive pairs we found. BMW Australia asks for as similar a rolling circumference as possible on xDrive models and publishes no percentage.
Get a plain-English explanation of your results and what they mean for your vehicle.
How this calculator works
Tire dimensions are derived from P‑metric sizes or width/aspect/rim fields: sidewall height = width × aspect ratio ÷ 100, overall diameter = rim diameter + 2 × sidewall height, circumference = π × diameter. These equations are standard across leading tire calculators and technical references.
The front to rear difference is the gap in overall diameter as a share of the smaller tire, compared with the largest gap among the factory xDrive pairs BMW lists. BMW publishes no percentage; its Australian tyre FAQ asks for as similar a rolling circumference as possible on xDrive models.
BMW xDrive Factory Front and Rear Tire Pairs
Sizes from BMW Group PressClub specifications. Gaps are calculated from the nominal overall diameter.
| Model | Front | Rear | Gap |
|---|---|---|---|
| M340i xDrive (3 Series Touring spec sheet) | 225/45R18 | 255/40R18 | 0.23% |
| X5 (2019) 21 inch option | 275/40R21 | 315/35R21 | 0.07% |
| X5 (2019) 22 inch option | 275/35R22 | 315/30R22 | 0.47% |
| M5 (2025) xDrive | 285/40R20 | 295/35R21 | 0.53% |
| M3 / M4 (2025) 19 and 20 inch | 275/35R19 | 285/30R20 | 0.58% |
| M3 (2025) standard 18 and 19 inch | 275/40R18 | 285/35R19 | 0.72% |
| Example above the factory range (not a BMW size) | 225/45R18 | 255/35R18 | 3.78% |
How the Difference Is Calculated, and Sources
Rolling diameter
Rim x 25.4 + 2 x width x aspect / 100, in mm. Front and rear are compared on this nominal diameter.
Front to rear difference
|front - rear| / smaller diameter x 100. M3/M4: (679.0 - 675.1) / 675.1 = 0.58%.
Compared with factory pairs
The result is checked against the largest gap among the BMW pairs listed here (0.72%).
Revs per mile
63,360 / circumference in inches for each axle; the gap in wheel turns per mile follows from the diameters.
| Source | Statement (paraphrased) |
|---|---|
| BMW Australia, tyre FAQ | On xDrive models all four tyres should have as similar a rolling circumference as possible. No percentage is given. |
| BMW Group PressClub, technical specifications | List the front and rear tire sizes for the models in the table above, several of them staggered, which is where the factory gap range on this page comes from. |
| Continental Tire, plus-sizing guidance | Keep the rolling circumference within 3% of the original when changing tire size. This is a general limit, not an xDrive tolerance. |
See also the AWD tire size guide, the tire size difference calculator, the staggered fitment calculator and the BMW tire size guide.
How to Check an xDrive Tire Setup
- 1Enter the front tire size as a code such as 275/35R19, or by width, aspect ratio and rim.
- 2Open the rear tab and enter the rear size.
- 3Read the front to rear difference in percent, mm and revs per mile.
- 4Compare it with the factory range and confirm with a BMW dealer if it is above it.