2021 BMW 8 Series 840i
The 2021 BMW 8 Series 840i 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 245/45R18
The 245/45R18 fitted to the 2021 BMW 8 Series has a section width of 245mm and an aspect ratio of 45%, mounted on a 18-inch rim. That gives a sidewall height of 110.3mm (4.34") and an overall outside diameter of 677.7mm (26.68"). At highway speed this tire completes roughly 470 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 255/38R19 (plus-one). For a softer ride or winter setup, a 235/52R17 (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: 245/45R18 up front and 275/40R18 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) |
|---|---|---|---|
| 840i | 245/45R18 Rear: 275/40R18 | 18" x 8.0 | ET26 |
Frequently Asked Questions
What tire size does the 2021 BMW 8 Series 840i use?
The 2021 BMW 8 Series 840i uses 245/45R18 tires as standard equipment.
What is the bolt pattern of the 2021 BMW 8 Series 840i?
The 2021 BMW 8 Series 840i has a 5x112 bolt pattern with a center bore of 66.6mm.
What is the wheel offset of the 2021 BMW 8 Series 840i?
The 2021 BMW 8 Series 840i has a wheel offset of ETET26.