What is 285/65R20 in inches?

A 285/65R20 tire is 34.59 inches tall and 11.2 inches wide, with a 7.29-inch sidewall, mounted on a 20-inch wheel. In metric that is 879 mm tall and 285 mm wide. The circumference is 108.66 inches.

How tall is a 285/65R20 tire?

34.59 inches, or 879 mm. That is the overall diameter, wheel included. It turns about 583 times per mile, which is what your speedometer counts.

What do the numbers in 285/65R20 mean?

285 is the tread width in millimeters, 65 is the aspect ratio — the sidewall height as a percentage of the tread width — and 20 is the wheel diameter in inches. So the sidewall is 285 × 65% = 185.3 mm tall.

285/65R20

A 285/65R20 tire is 34.59 inches tall and 11.2 inches wide, with a 7.29-inch sidewall, mounted on a 20-inch wheel.

Overall diameter

34.59″

879 mm

Sidewall height

7.29″

185.3 mm

Tread width

285 mm

11.2″

Circumference

108.66″

9.1 ft

Revs per mile

583

362 per km

Wheel diameter

20″

aspect ratio 65%

Compare vs 275/55R20 Compare with a custom size

Cross-section

Overall diameter: 34.59″
Sidewall (each side): 7.29″
Wheel: 20″

285/65R20 in inches and millimeters

Every dimension of a 285/65R20, converted both ways. Calculated from the size code, accurate to about 1%.

Measurement	Inches	Millimeters
Overall diameter (height)	34.59″	879 mm
Tread width	11.2″	285 mm
Sidewall height	7.29″	185.3 mm
Wheel diameter	20″	508 mm
Circumference	108.66″	2760 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.

285/65R20 compared with other sizes

All 22 practical swaps involving 285/65R20 — diameter change, speedometer impact and a fit verdict for each.

285/65R20 → 285/70R18

285/70R18

Diameter +2.6% · This fits

285/65R20 → 295/70R18

295/70R18

Diameter +1.0% · This fits

285/65R20 → 275/60R20

275/60R20

Diameter +4.8% · Borderline. Check clearance first

285/65R20 → 275/65R20

275/65R20

Diameter +1.5% · This fits

285/65R20 → 285/60R20

285/60R20

Diameter +3.4% · Borderline. Check clearance first

295/65R20 → 285/65R20

295/65R20

Diameter +1.5% · This fits

275/65R20 → 285/65R20

275/65R20

Diameter −1.5% · This fits

295/60R20 → 285/65R20

295/60R20

Diameter −1.9% · This fits

285/60R20 → 285/65R20

285/60R20

Diameter −3.2% · Borderline. Check clearance first

305/55R20 → 285/65R20

305/55R20

Diameter −4.0% · Borderline. Check clearance first

275/60R20 → 285/65R20

275/60R20

Diameter −4.6% · Borderline. Check clearance first

295/70R18 → 285/65R20

295/70R18

Diameter −0.9% · This fits

285/70R18 → 285/65R20

285/70R18

Diameter −2.5% · This fits

285/50R22 → 285/65R20

285/50R22

Diameter −3.9% · Borderline. Check clearance first

275/70R18 → 285/65R20

275/70R18

Diameter −4.1% · Borderline. Check clearance first

275/50R22 → 285/65R20

275/50R22

Diameter −5.1% · Too big a jump

305/45R22 → 285/65R20

305/45R22

Diameter −5.1% · Too big a jump

285/65R20 → 295/60R20

295/60R20

Diameter +1.9% · This fits

285/65R20 → 295/65R20

295/65R20

Diameter −1.5% · This fits

285/65R20 → 305/55R20

305/55R20

Diameter +4.1% · Borderline. Check clearance first

285/65R20 → 285/50R22

285/50R22

Diameter +4.1% · Borderline. Check clearance first

285/65R20 → 275/55R20

275/55R20

Diameter +8.4% · Too big a jump

Common questions

What is 285/65R20 in inches?: A 285/65R20 tire is 34.59 inches tall and 11.2 inches wide, with a 7.29-inch sidewall, mounted on a 20-inch wheel. In metric that is 879 mm tall and 285 mm wide. The circumference is 108.66 inches.
How tall is a 285/65R20 tire?: 34.59 inches, or 879 mm. That is the overall diameter, wheel included. It turns about 583 times per mile, which is what your speedometer counts.
What do the numbers in 285/65R20 mean?: 285 is the tread width in millimeters, 65 is the aspect ratio — the sidewall height as a percentage of the tread width — and 20 is the wheel diameter in inches. So the sidewall is 285 × 65% = 185.3 mm tall.