What is 235/45R18 in inches?

A 235/45R18 tire is 26.33 inches tall and 9.3 inches wide, with a 4.16-inch sidewall, mounted on a 18-inch wheel. In metric that is 669 mm tall and 235 mm wide. The circumference is 82.71 inches.

How tall is a 235/45R18 tire?

26.33 inches, or 669 mm. That is the overall diameter, wheel included. It turns about 766 times per mile, which is what your speedometer counts.

What do the numbers in 235/45R18 mean?

235 is the tread width in millimeters, 45 is the aspect ratio — the sidewall height as a percentage of the tread width — and 18 is the wheel diameter in inches. So the sidewall is 235 × 45% = 105.8 mm tall.

235/45R18

Most common 18″ size

A 235/45R18 tire is 26.33 inches tall and 9.3 inches wide, with a 4.16-inch sidewall, mounted on a 18-inch wheel.

Common fitments: Camry, Accord, Model 3

Overall diameter

26.33″

669 mm

Sidewall height

4.16″

105.8 mm

Tread width

235 mm

9.3″

Circumference

82.71″

6.9 ft

Revs per mile

766

476 per km

Wheel diameter

18″

aspect ratio 45%

Compare 235/45R18 in the tool Compare with a custom size

Cross-section

Overall diameter: 26.33″
Sidewall (each side): 4.16″
Wheel: 18″

235/45R18 in inches and millimeters

Every dimension of a 235/45R18, converted both ways. Calculated from the size code, accurate to about 1%.

Measurement	Inches	Millimeters
Overall diameter (height)	26.33″	669 mm
Tread width	9.3″	235 mm
Sidewall height	4.16″	105.8 mm
Wheel diameter	18″	457 mm
Circumference	82.71″	2101 mm

Nominal dimensions from the size code. A real tire varies by a few millimeters between manufacturers, and a loaded tire sits slightly shorter than its free diameter.

235/45R18 compared with other sizes

All 54 practical swaps involving 235/45R18 — diameter change, speedometer impact and a fit verdict for each.

235/45R18 → 215/60R16

215/60R16

Diameter +0.6% · This fits

235/45R18 → 225/60R16

225/60R16

Diameter −1.1% · This fits

235/45R18 → 215/55R17

215/55R17

Diameter +0.1% · This fits

235/45R18 → 225/40R18

225/40R18

Diameter +4.9% · Borderline. Check clearance first

235/45R18 → 225/45R18

225/45R18

Diameter +1.4% · This fits

235/45R18 → 235/40R18

235/40R18

Diameter +3.6% · Borderline. Check clearance first

255/40R18 → 235/45R18

255/40R18

Diameter −1.1% · This fits

225/45R18 → 235/45R18

225/45R18

Diameter −1.3% · This fits

245/45R18 → 235/45R18

245/45R18

Diameter +1.3% · This fits

235/40R18 → 235/45R18

235/40R18

Diameter −3.5% · Borderline. Check clearance first

235/50R18 → 235/45R18

235/50R18

Diameter +3.5% · Borderline. Check clearance first

245/40R18 → 235/45R18

245/40R18

Diameter −2.3% · This fits

255/45R18 → 235/45R18

255/45R18

Diameter +2.7% · This fits

235/40R19 → 235/45R18

235/40R19

Diameter +0.3% · This fits

225/40R18 → 235/45R18

225/40R18

Diameter −4.7% · Borderline. Check clearance first

215/55R17 → 235/45R18

215/55R17

Diameter −0.1% · This fits

205/65R16 → 235/45R18

205/65R16

Diameter +0.6% · This fits

215/60R16 → 235/45R18

215/60R16

Diameter −0.6% · This fits

255/35R19 → 235/45R18

255/35R19

Diameter −1.1% · This fits

225/60R16 → 235/45R18

225/60R16

Diameter +1.2% · This fits

235/45R18 → 235/50R18

235/50R18

Diameter −3.4% · Borderline. Check clearance first

235/45R18 → 245/40R18

245/40R18

Diameter +2.4% · This fits

235/45R18 → 245/45R18

245/45R18

Diameter −1.3% · This fits

235/45R18 → 235/40R19

235/40R19

Diameter −0.3% · This fits

235/45R18 → 245/35R19

245/35R19

Diameter +2.2% · This fits

235/45R18 → 245/40R19

245/40R19

Diameter −1.5% · This fits

235/45R18 → 255/35R19

255/35R19

Diameter +1.1% · This fits

235/45R18 → 245/35R20

245/35R20

Diameter −1.6% · This fits

235/45R18 → 205/65R16

205/65R16

Diameter −0.6% · This fits

235/45R18 → 255/40R18

255/40R18

Diameter +1.1% · This fits

235/45R18 → 255/45R18

255/45R18

Diameter −2.6% · This fits

235/60R18 → 235/45R18

235/60R18

Diameter +10.5% · Too big a jump

255/55R18 → 235/45R18

255/55R18

Diameter +10.3% · Too big a jump

265/60R18 → 235/45R18

265/60R18

Diameter +15.9% · Too big a jump

225/60R18 → 235/45R18

225/60R18

Diameter +8.7% · Too big a jump

235/55R18 → 235/45R18

235/55R18

Diameter +7.0% · Too big a jump

235/65R18 → 235/45R18

235/65R18

Diameter +14.1% · Too big a jump

245/60R18 → 235/45R18

245/60R18

Diameter +12.3% · Too big a jump

245/65R18 → 235/45R18

245/65R18

Diameter +16.0% · Too big a jump

255/60R18 → 235/45R18

255/60R18

Diameter +14.1% · Too big a jump

255/65R18 → 235/45R18

255/65R18

Diameter +17.9% · Too big a jump

255/70R18 → 235/45R18

255/70R18

Diameter +21.8% · Too big a jump

265/65R18 → 235/45R18

265/65R18

Diameter +19.9% · Too big a jump

265/70R18 → 235/45R18

265/70R18

Diameter +23.9% · Too big a jump

275/60R18 → 235/45R18

275/60R18

Diameter +17.7% · Too big a jump

275/65R18 → 235/45R18

275/65R18

Diameter +21.8% · Too big a jump

275/70R18 → 235/45R18

275/70R18

Diameter +25.9% · Too big a jump

285/60R18 → 235/45R18

285/60R18

Diameter +19.5% · Too big a jump

285/65R18 → 235/45R18

285/65R18

Diameter +23.8% · Too big a jump

285/70R18 → 235/45R18

285/70R18

Diameter +28.0% · Too big a jump

295/70R18 → 235/45R18

295/70R18

Diameter +30.1% · Too big a jump

305/60R18 → 235/45R18

305/60R18

Diameter +23.1% · Too big a jump

235/45R18 → 225/45R17

225/45R17

Diameter +5.4% · Too big a jump

245/40R19 → 235/45R18

245/40R19

Diameter +1.5% · This fits

Common questions

What is 235/45R18 in inches?: A 235/45R18 tire is 26.33 inches tall and 9.3 inches wide, with a 4.16-inch sidewall, mounted on a 18-inch wheel. In metric that is 669 mm tall and 235 mm wide. The circumference is 82.71 inches.
How tall is a 235/45R18 tire?: 26.33 inches, or 669 mm. That is the overall diameter, wheel included. It turns about 766 times per mile, which is what your speedometer counts.
What do the numbers in 235/45R18 mean?: 235 is the tread width in millimeters, 45 is the aspect ratio — the sidewall height as a percentage of the tread width — and 18 is the wheel diameter in inches. So the sidewall is 235 × 45% = 105.8 mm tall.