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.
OE on the Chevrolet Corvette C5 rear (1997-2004) on 18x9.5" wheels. Load index 99Y or 103Y reinforced. Muscle-car rear-axle staple — almost always paired with a narrower front (usually 245/45R18).
Low-profile sizes in this group prioritize steering response and lateral grip over sidewall protection from pothole impacts. Curb-rash on the rim and pinched sidewalls are the dominant failure modes; insurance-claim data shows these sizes register two to three times more wheel damage than 50+ aspect ratios. Plan for a spare set of rims if the route includes broken urban pavement.
| Tire Code | 275/40R18 |
| Section Width | 275 mm |
| Aspect Ratio | 40% |
| Rim Diameter | 18" |
| Sidewall Height | 110.0 mm |
| Overall Diameter | 677.2 mm / 26.66" |
| Circumference | 2127.5 mm / 83.76" |
| Revolutions per km | 470.0 |
| Revolutions per mile | 756.5 |
| Tire Code | OD (mm) | Δ mm | Δ % | 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 |