About the 275/40R18 Tire

The 275/40R18 is a common tire size for performance and sports cars such as BMW 3 Series, Volkswagen GTI, and Audi A4.

With a 110.0 mm sidewall (40% aspect ratio), this low-profile tire delivers sharp steering response and precise cornering grip, though the ride feels firmer over rough surfaces.

Compared to the baseline 235/45R18, this tire's overall diameter differs by +1.3% — a speedometer calibrated for 235/45R18 would read 98.7 km/h at an actual 100 km/h.

When replacing, verify that your wheel well can accommodate the 677.2 mm overall diameter. Keep speedometer deviation within ±3% for safety and legal compliance.

Tire Measurements

Tire Code275/40R18
Section Width275 mm
Aspect Ratio40%
Rim Diameter18"
Sidewall Height110.0 mm
Overall Diameter677.2 mm / 26.66"
Circumference2127.5 mm / 83.76"
Revolutions per km470.0
Revolutions per mile756.5

Adjacent Size Comparison

Tire Code OD (mm)Δ mmΔ % Speedo at 100 km/h
245/40R18 653.2 -24.0 -3.5% 103.7
255/40R18 661.2 -16.0 -2.4% 102.4
275/40R18 (current) 677.2 — — 100.0
275/40R19 702.6 +25.4 +3.8% 96.4

Frequently Asked Questions

What is the overall diameter of a 275/40R18 tire?
The overall diameter is 677.2 mm (26.66 in), with a 110.0 mm sidewall on a 18-inch rim.
How many revolutions per kilometer does a 275/40R18 tire make?
It makes 470.0 revolutions per kilometer, with a circumference of 2127.5 mm.
What vehicles commonly use 275/40R18 tires?
The 275/40R18 is standard OEM equipment on performance and sports cars such as BMW 3 Series, Volkswagen GTI, and Audi A4. Always check your owner's manual or door placard before switching sizes.

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