2021 BMW 3 Series: the quick answer
The 2021 BMW 3 Series ships with 225/45R18 tires on the base trim — that's an overall diameter of 26″. The 225 mm width and 45% sidewall ratio give you 101.3 mm of sidewall cushion between the rim and the road.
Tire fitment
2021 BMW 3 Series tire size
The 2021 BMW 3 Series base tire size is 225/45R18 — 225 mm wide with a 45% aspect ratio on 18″ rims. 3 OEM sizes are available across trims.
2021 BMW 3 Series
225/45R1826″ overall diameter · 101.3 mm sidewall · ~777 rev/mi
| Trim | Tire size | Rim | Diameter | vs Base |
|---|---|---|---|---|
| 330i ★ | 225/45R18 | 7.5×18″ | 26″ (659.7 mm) | — |
| M Sport/M340i (front) | 225/40R19 | 8×19″ | 26.1″ (662.6 mm) | +0.44% |
| M Sport/M340i (rear) | 255/35R19 | 8.5×19″ | 26″ (661.1 mm) | +0.21% |
Staggered: 225/40R19 front, 255/35R19 rear.
Before you buy tires
Match the load index and speed rating from your door-jamb placard — not just the size. If you're switching sizes, keep the overall diameter within ~3% to avoid speedometer error and potential ABS/traction-control issues.
Factory fitment for the 2021 BMW 3 Series; verify against your door-jamb placard or owner's manual.
FAQ
What tire size does the 2021 BMW 3 Series use?
The base 2021 BMW 3 Series uses 225/45R18 tires — 225 mm wide, 45% aspect ratio, on 18-inch rims. The overall diameter is 26″ (659.7 mm). Higher trims use different sizes — see the table above. Confirm against your door-jamb placard.
Can I use a different tire size on my 2021 3 Series?
Yes, within limits. Keep the overall diameter within about 3% of 26″ to avoid speedometer error and clearance issues. A wider tire may improve grip, but match the load and speed ratings your 3 Series requires.
What is the overall diameter of 225/45R18 tires?
225/45R18 tires have an overall diameter of 26″ (659.7 mm), with a 101.3 mm sidewall height. That's about 777 revolutions per mile.
The 2021 BMW 3 Series tire sizes shown are OEM factory fitments. Confirm your exact tire size, load rating, and speed rating against the door-jamb placard or owner's manual before buying tires.