285/40R21 tire size

A 285/40R21 tire is 29.98 in (761.4 mm) tall and 11.22 in (285.0 mm) wide, and turns 673 revolutions per mile.

• 29.98 inOverall diameter
• 4.49 inSidewall height
• 673Revolutions per mile
• 30.0x11.2R21Flotation equivalent

285/40R21 is a 21-inch tire with a 285 mm (11.22 in) section width and a 40% aspect ratio, giving a 4.49-inch sidewall and a flotation-style size of about 30.0x11.2R21.

Its overall diameter is 29.98 inches, so it rolls 94.2 inches per revolution and turns about 673 times per mile.

66 other sizes in this list are within 3% of that diameter.

Compare 285/40R21 with plausible swaps

• 275/50R19 vs 285/40R21 (−0.50%)
• 255/55R19 vs 285/40R21 (+0.22%)
• 235/60R19 vs 285/40R21 (+0.42%)
• 275/45R20 vs 285/40R21 (−0.77%)
• 255/50R20 vs 285/40R21 (+0.21%)
• 285/45R20 vs 285/40R21 (+0.41%)
• 235/55R20 vs 285/40R21 (+0.67%)
• 285/35R21 vs 285/40R21 (−3.74%)
• 265/40R21 vs 285/40R21 (−2.10%)
• 275/40R21 vs 285/40R21 (−1.05%)
• 245/45R21 vs 285/40R21 (−0.99%)
• 315/35R21 vs 285/40R21 (−0.99%)
• 285/40R21 vs 255/45R21 (+0.20%)
• 285/40R21 vs 295/40R21 (+1.05%)
• 285/40R21 vs 285/45R21 (+3.74%)
• 285/40R21 vs 285/35R22 (−0.41%)
• 285/40R21 vs 255/40R22 (+0.18%)
• 285/40R21 vs 265/40R22 (+1.23%)

Sizes within 3% of 29.98 in diameter

• 275/60R17 29.99 in (+0.05%)
• 30x9.50R15 30.00 in (+0.08%)
• 235/70R17 29.95 in (−0.08%)
• 235/65R18 30.03 in (+0.17%)
• 255/40R22 30.03 in (+0.18%)
• 255/45R21 30.04 in (+0.20%)
• 255/50R20 30.04 in (+0.21%)
• 275/55R18 29.91 in (−0.22%)
• 255/55R19 30.04 in (+0.22%)
• 255/60R18 30.05 in (+0.24%)
• 255/65R17 30.05 in (+0.25%)
• 255/70R16 30.06 in (+0.26%)
• 235/75R16 29.88 in (−0.33%)
• 285/45R20 30.10 in (+0.41%)
• 285/35R22 29.85 in (−0.41%)
• 235/60R19 30.10 in (+0.42%)
• 275/50R19 29.83 in (−0.50%)
• 235/55R20 30.18 in (+0.67%)
• 275/45R20 29.74 in (−0.77%)
• 245/45R21 29.68 in (−0.99%)
• 315/35R21 29.68 in (−0.99%)
• 225/75R17 30.29 in (+1.04%)
• 275/40R21 29.66 in (−1.05%)
• 295/40R21 30.29 in (+1.05%)
• 245/50R20 29.65 in (−1.10%)
• 245/55R19 29.61 in (−1.22%)
• 265/70R15 29.61 in (−1.23%)
• 305/40R20 29.61 in (−1.23%)
• 265/40R22 30.35 in (+1.23%)
• 245/60R18 29.57 in (−1.34%)
• 215/85R16 30.39 in (+1.38%)
• 265/45R21 30.39 in (+1.38%)
• 305/35R22 30.41 in (+1.43%)
• 245/65R17 29.54 in (−1.46%)
• 265/60R17 29.52 in (−1.52%)
• 265/50R20 30.43 in (+1.52%)
• 245/70R16 29.50 in (−1.58%)
• 295/45R20 30.45 in (+1.59%)
• 245/75R16 30.47 in (+1.64%)
• 265/55R19 30.48 in (+1.67%)
• 245/75R15 29.47 in (−1.69%)
• 245/70R17 30.50 in (+1.76%)
• 315/30R22 29.44 in (−1.79%)
• 265/60R18 30.52 in (+1.81%)
• 265/50R19 29.43 in (−1.81%)
• 245/65R18 30.54 in (+1.88%)
• 275/25R24 29.41 in (−1.88%)
• 265/65R17 30.56 in (+1.96%)
• 265/45R20 29.39 in (−1.96%)
• 265/70R16 30.61 in (+2.10%)
• 265/40R21 29.35 in (−2.10%)
• 245/55R20 30.61 in (+2.11%)
• 235/45R21 29.33 in (−2.17%)
• 265/75R15 30.65 in (+2.25%)
• 265/35R22 29.30 in (−2.25%)
• 295/40R20 29.29 in (−2.29%)
• 275/40R22 30.66 in (+2.29%)
• 225/75R16 29.29 in (−2.30%)
• 285/30R24 30.73 in (+2.52%)
• 275/45R21 30.74 in (+2.56%)
• 235/55R19 29.18 in (−2.67%)
• 305/45R20 30.81 in (+2.77%)
• 295/35R21 29.13 in (−2.82%)
• 275/50R20 30.83 in (+2.84%)
• 235/60R18 29.10 in (−2.92%)
• 285/45R19 29.10 in (−2.93%)

Open 285/40R21 in the tire size calculator

Source: Calculated from standard tire geometry formulas. Verified 2026-09-27. How these numbers are calculated.