Steering feel
Softer, more relaxed turn-in
More sidewall flex before grip arrives — comfort-tuned, calm at speed.
Tire size meaning
255/55 R18
What the numbers on a 255/55 R18 tire actually mean — width, sidewall, construction and rim — explained in plain language with real-world driving context.
Direct answer
What does 255/55 R18 mean?
255/55 R18 is a metric tire size: 255 mm wide, a sidewall 55% of that width (140 mm), radial construction, fitted to a 18-inch wheel. Overall diameter ≈ 738 mm.
- 255
- Section width in mm (sidewall to sidewall).
- 55
- Aspect ratio — sidewall is 55% of width (140 mm).
- R
- Radial construction — the modern layered build.
- 18
- Wheel rim diameter in inches (457 mm).
Ø 738 mm · 29.04″ · 431 revs/km
Dimensional breakdown
- Section width
- 255 mm
- Aspect ratio
- 55%
- Sidewall height
- 140.3 mm
- Rim diameter
- 18″ (457.2 mm)
- Overall diameter
- 738 mm
- Circumference
- 2.318 m
- Revs per km
- 431
- Construction
- Radial (R)
What 255/55 R18 feels like on the road
A 255/55 R18 tire is a tall-sidewall comfort or off-road profile. With a sidewall of 140 mm, it absorbs bumps and rough surfaces well, ideal for comfort cruisers, SUVs and light off-road use.
The 255 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 431 revolutions per kilometre — the figure your speedometer and ABS were calibrated against if 255/55 R18 is the OEM specification.
Common alternatives to 255/55 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 255/55 R18 usually feels like
A driver-perspective read on this size — steering, comfort, highway stability and rough-road behavior.
Ride comfort
Softer over potholes
Tall sidewall absorbs expansion joints and broken tarmac — great for long drives.
Highway stability
Planted at highway speed
Wider contact patch resists crosswinds and tramlining — strong straight-line confidence.
Pothole comfort
Forgiving over impacts
Sidewall cushions the rim from sharp edges — ideal for poor roads.
Sporty vs OEM tone
Comfort-leaning OEM setup
Tuned for ride quality and economy over outright bite.
Sidewall140 mm
Ø738 mm
Width255 mm
Revs/km431
Related tire sizes for 255/55 R18
Explore neighbouring sizes by intent — similar, wider, lower-profile, OEM-safe, or aggressive. Each link opens a full side-by-side comparison.