Steering feel
Sharper steering response
Short sidewall loads the contact patch fast — quick turn-in and confident on-center feel.
Tire size meaning
245/40 R18
What the numbers on a 245/40 R18 tire actually mean — width, sidewall, construction and rim — explained in plain language with real-world driving context.
Direct answer
What does 245/40 R18 mean?
245/40 R18 is a metric tire size: 245 mm wide, a sidewall 40% of that width (98 mm), radial construction, fitted to a 18-inch wheel. Overall diameter ≈ 653 mm.
- 245
- Section width in mm (sidewall to sidewall).
- 40
- Aspect ratio — sidewall is 40% of width (98 mm).
- R
- Radial construction — the modern layered build.
- 18
- Wheel rim diameter in inches (457 mm).
Ø 653 mm · 25.72″ · 487 revs/km
Dimensional breakdown
- Section width
- 245 mm
- Aspect ratio
- 40%
- Sidewall height
- 98.0 mm
- Rim diameter
- 18″ (457.2 mm)
- Overall diameter
- 653 mm
- Circumference
- 2.052 m
- Revs per km
- 487
- Construction
- Radial (R)
What 245/40 R18 feels like on the road
A 245/40 R18 tire is a low-profile sporty tire. With a sidewall of 98 mm, it gives precise turn-in with a reasonable ride compromise — typical for sport sedans and hot hatches.
The 245 mm contact width delivers maximum contact patch for high-performance and SUV applications. Combined with a 18-inch wheel, this size is most commonly found on mid-size sedans, sport trims and modern crossovers.
At highway speed each tire completes about 487 revolutions per kilometre — the figure your speedometer and ABS were calibrated against if 245/40 R18 is the OEM specification.
Common alternatives to 245/40 R18
Sizes within ±3% overall diameter — generally safe swaps for speedometer accuracy and clearance. Click any size to open a full side-by-side comparison.
Driver feel · telemetry
What 245/40 R18 usually feels like
A driver-perspective read on this size — steering, comfort, highway stability and rough-road behavior.
Ride comfort
Firmer over rough pavement
Short sidewall transmits more imperfections and increases wheel-damage risk on potholes.
Highway stability
Planted at highway speed
Wider contact patch resists crosswinds and tramlining — strong straight-line confidence.
Pothole comfort
Less margin against pothole damage
Run wider arc around potholes — short sidewall means the rim takes more of the hit.
Sporty vs OEM tone
Aggressive performance setup
A performance fingerprint — sharp, planted, low and committed.
Sidewall98 mm
Ø653 mm
Width245 mm
Revs/km487
Related tire sizes for 245/40 R18
Explore neighbouring sizes by intent — similar, wider, lower-profile, OEM-safe, or aggressive. Each link opens a full side-by-side comparison.