Tire size meaning

255/45 R18

What the numbers on a 255/45 R18 tire actually mean — width, sidewall, construction and rim — explained in plain language with real-world driving context.

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Direct answer

What does 255/45 R18 mean?

255/45 R18 is a metric tire size: 255 mm wide, a sidewall 45% of that width (115 mm), radial construction, fitted to a 18-inch wheel. Overall diameter ≈ 687 mm.

255
Section width in mm (sidewall to sidewall).
45
Aspect ratio — sidewall is 45% of width (115 mm).
R
Radial construction — the modern layered build.
18
Wheel rim diameter in inches (457 mm).

Ø 687 mm · 27.04″ · 464 revs/km

Section width 255 mmSidewall 115 mmR18 (457 mm)Ø 687 mm (27.04″)

Dimensional breakdown

Section width
255 mm
Aspect ratio
45%
Sidewall height
114.8 mm
Rim diameter
18″ (457.2 mm)
Overall diameter
687 mm
Circumference
2.157 m
Revs per km
464
Construction
Radial (R)

What 255/45 R18 feels like on the road

A 255/45 R18 tire is a low-profile sporty tire. With a sidewall of 115 mm, it gives precise turn-in with a reasonable ride compromise — typical for sport sedans and hot hatches.

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 464 revolutions per kilometre — the figure your speedometer and ABS were calibrated against if 255/45 R18 is the OEM specification.

Common alternatives to 255/45 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 255/45 R18 usually feels like

A driver-perspective read on this size — steering, comfort, highway stability and rough-road behavior.

Steering feel

Balanced, OEM-style response

A familiar OEM feel — predictable inputs without trade-offs.

Ride comfort

Comfortable daily ride

A balanced compromise — bumps muted, steering still precise.

Highway stability

Planted at highway speed

Wider contact patch resists crosswinds and tramlining — strong straight-line confidence.

Pothole comfort

Reasonable impact protection

Enough sidewall to protect the rim from typical urban hits.

Sporty vs OEM tone

Balanced everyday character

A factory-style balance between feel, comfort and grip.

Sidewall115 mm
Ø687 mm
Width255 mm
Revs/km464

Related tire sizes for 255/45 R18

Explore neighbouring sizes by intent — similar, wider, lower-profile, OEM-safe, or aggressive. Each link opens a full side-by-side comparison.

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Frequently asked questions