2021 BMW 8 Series M850i xDrive
The 2021 BMW 8 Series M850i xDrive tire size and wheel specifications below reflect standard OEM reference fitment data for this trim level.
Detailed tire and wheel breakdown for the 2021 BMW 8 Series
Tire geometry â 245/35R20
The 245/35R20 fitted to the 2021 BMW 8 Series has a section width of 245mm and an aspect ratio of 35%, mounted on a 20-inch rim. That gives a sidewall height of 85.8mm (3.38") and an overall outside diameter of 679.5mm (26.75"). At highway speed this tire completes roughly 468 revolutions per kilometre, which is what your speedometer and odometer are calibrated against.
Plus-sizing window
If you want to upsize wheels on the 2021 BMW 8 Series while keeping the speedometer accurate, target a 255/29R21 (plus-one). For a softer ride or winter setup, a 235/42R19 (minus-one) keeps the overall diameter within Âą3% of stock, which is the industry tolerance for ABS and stability control to stay calibrated.
Wheel fitment specs
The 2021 BMW 8 Series uses a 5x112 bolt pattern with a 66.6mm hub bore. Safe rim width range for the OEM tire is 7.5J â 8.5J, and offsets in the ET21 â ET31 window will clear suspension and fender without rubbing on most setups.
Staggered setup notes
The 2021 BMW 8 Series ships staggered: 245/35R20 up front and 275/30R20 on the rear. That is a 275mm vs 245mm width difference â do not rotate front-to-rear, and replace tires in axle pairs to keep ABS and traction control balanced.
Tire pressure guidance
Manufacturer-recommended cold tire pressure for the 2021 BMW 8 Series is printed on the driver-side door jamb sticker â always defer to that value, not to the maximum pressure printed on the tire sidewall. Check pressure monthly and before long trips; under-inflation by 20% can reduce tread life by 25%.
Fitment Specifications
| Engine & Trim | Tire Size | Rim Size | Offset (ET) |
|---|---|---|---|
| M850i xDrive | 245/35R20 Rear: 275/30R20 | 20" x 8.0 | ET26 |
Frequently Asked Questions
What tire size does the 2021 BMW 8 Series M850i xDrive use?
The 2021 BMW 8 Series M850i xDrive uses 245/35R20 tires as standard equipment.
What is the bolt pattern of the 2021 BMW 8 Series M850i xDrive?
The 2021 BMW 8 Series M850i xDrive has a 5x112 bolt pattern with a center bore of 66.6mm.
What is the wheel offset of the 2021 BMW 8 Series M850i xDrive?
The 2021 BMW 8 Series M850i xDrive has a wheel offset of ETET26.