2018 BMW 230i — xDrive Coupe Luxury

The 2018 BMW 230i xDrive Coupe Luxury shipped with 3 different factory tire sizes, depending on the wheel package it left the factory with (this can also reflect a staggered front/rear setup). Check your tire sidewall or door placard to confirm which one applies to your vehicle.

This trim shipped with more than one tire size (staggered fitment, front/rear, or optional wheel package). Confirm which one matches your vehicle by checking your tire sidewall or door placard.

225/40R18

Section width225 mm
Aspect ratio (sidewall height)40% (90 mm)
Rim diameter18"
Overall tire diameter~25.1"
Revolutions per mile~804

Compare prices at:

225/40R18 (Front)

Section width225 mm
Aspect ratio (sidewall height)40% (90 mm)
Rim diameter18"
Overall tire diameter~25.1"
Revolutions per mile~804

Compare prices at:

245/35R18 (Rear)

Section width245 mm
Aspect ratio (sidewall height)35% (85.8 mm)
Rim diameter18"
Overall tire diameter~24.8"
Revolutions per mile~815

Compare prices at:

What this size means for your BMW 230i

On the 2018 BMW 230i xDrive Coupe Luxury, the factory 225/40R18 measures about 25.1″ in overall diameter with a 90 mm (3.5″) sidewall, and completes roughly 804 revolutions per mile. Its 40-series aspect ratio gives a low-profile sidewall tuned for sharper handling, common on sport trims and larger-wheel packages. In tire terms it is a passenger (P-metric / Euro-metric) size.

The 225/40R18 and 225/40R18 roll within 0″ (0%) of each other in overall diameter, so they are interchangeable from a speedometer standpoint — the second size is an optional wheel package rather than a different rolling size.

Other 2018 BMW 230i trims

BMW 230i tire sizes by year

See every BMW 230i year & trim →

How to read a tire size

A tire size like 225/45R17 breaks down into three parts: the first number is the section width in millimeters (the tire's width from sidewall to sidewall), the second is the aspect ratio — the sidewall's height as a percentage of that width — and the number after the "R" is the rim diameter in inches. A letter prefix (P or LT) indicates Passenger or Light Truck construction; its absence usually means Euro-metric sizing.

Some trucks and off-road tires instead use "flotation" sizing, like 37X12.50R17 — here the numbers are the tire's overall diameter and width in inches directly, with the rim diameter last.

Always verify against the tire information placard on your driver's-side door jamb or your owner's manual before purchasing — tire size can vary by factory option package even within the same trim.