275/40R21 tire size

A 275/40R21 tire is 29.66 in (753.4 mm) tall and 10.83 in (275.0 mm) wide, and turns 680 revolutions per mile.

• 29.66 inOverall diameter
• 4.33 inSidewall height
• 680Revolutions per mile
• 29.7x10.8R21Flotation equivalent

275/40R21 is a 21-inch tire with a 275 mm (10.83 in) section width and a 40% aspect ratio, giving a 4.33-inch sidewall and a flotation-style size of about 29.7x10.8R21.

Its overall diameter is 29.66 inches, so it rolls 93.2 inches per revolution and turns about 680 times per mile.

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

Compare 275/40R21 with plausible swaps

• 265/50R19 vs 275/40R21 (−0.77%)
• 245/55R19 vs 275/40R21 (−0.17%)
• 275/50R19 vs 275/40R21 (+0.56%)
• 265/45R20 vs 275/40R21 (−0.92%)
• 305/40R20 vs 275/40R21 (−0.19%)
• 245/50R20 vs 275/40R21 (−0.05%)
• 275/45R20 vs 275/40R21 (+0.28%)
• 275/35R21 vs 275/40R21 (−3.65%)
• 255/40R21 vs 275/40R21 (−2.12%)
• 235/45R21 vs 275/40R21 (−1.13%)
• 265/40R21 vs 275/40R21 (−1.06%)
• 275/40R21 vs 245/45R21 (+0.07%)
• 275/40R21 vs 315/35R21 (+0.07%)
• 275/40R21 vs 285/40R21 (+1.06%)
• 275/40R21 vs 295/40R21 (+2.12%)
• 275/40R21 vs 275/45R21 (+3.65%)
• 275/40R21 vs 315/30R22 (−0.74%)
• 275/40R21 vs 285/35R22 (+0.65%)
• 275/40R21 vs 255/40R22 (+1.25%)

Sizes within 3% of 29.66 in diameter

• 245/50R20 29.65 in (−0.05%)
• 245/45R21 29.68 in (+0.07%)
• 315/35R21 29.68 in (+0.07%)
• 245/55R19 29.61 in (−0.17%)
• 265/70R15 29.61 in (−0.19%)
• 305/40R20 29.61 in (−0.19%)
• 275/45R20 29.74 in (+0.28%)
• 245/60R18 29.57 in (−0.29%)
• 245/65R17 29.54 in (−0.41%)
• 265/60R17 29.52 in (−0.48%)
• 245/70R16 29.50 in (−0.53%)
• 275/50R19 29.83 in (+0.56%)
• 245/75R15 29.47 in (−0.65%)
• 285/35R22 29.85 in (+0.65%)
• 235/75R16 29.88 in (+0.73%)
• 315/30R22 29.44 in (−0.74%)
• 265/50R19 29.43 in (−0.77%)
• 275/55R18 29.91 in (+0.84%)
• 275/25R24 29.41 in (−0.84%)
• 265/45R20 29.39 in (−0.92%)
• 235/70R17 29.95 in (+0.98%)
• 265/40R21 29.35 in (−1.06%)
• 285/40R21 29.98 in (+1.06%)
• 275/60R17 29.99 in (+1.11%)
• 235/45R21 29.33 in (−1.13%)
• 30x9.50R15 30.00 in (+1.14%)
• 265/35R22 29.30 in (−1.21%)
• 235/65R18 30.03 in (+1.23%)
• 295/40R20 29.29 in (−1.25%)
• 255/40R22 30.03 in (+1.25%)
• 225/75R16 29.29 in (−1.26%)
• 255/45R21 30.04 in (+1.26%)
• 255/50R20 30.04 in (+1.27%)
• 255/55R19 30.04 in (+1.29%)
• 255/60R18 30.05 in (+1.30%)
• 255/65R17 30.05 in (+1.31%)
• 255/70R16 30.06 in (+1.33%)
• 285/45R20 30.10 in (+1.47%)
• 235/60R19 30.10 in (+1.49%)
• 235/55R19 29.18 in (−1.63%)
• 235/55R20 30.18 in (+1.74%)
• 295/35R21 29.13 in (−1.79%)
• 235/60R18 29.10 in (−1.88%)
• 285/45R19 29.10 in (−1.90%)
• 255/70R15 29.06 in (−2.04%)
• 255/65R16 29.05 in (−2.06%)
• 255/60R17 29.05 in (−2.07%)
• 255/55R18 29.04 in (−2.08%)
• 255/50R19 29.04 in (−2.10%)
• 225/75R17 30.29 in (+2.11%)
• 255/45R20 29.04 in (−2.11%)
• 255/40R21 29.03 in (−2.12%)
• 295/40R21 30.29 in (+2.12%)
• 235/65R17 29.03 in (−2.14%)
• 255/35R22 29.03 in (−2.14%)
• 285/40R20 28.98 in (−2.31%)
• 265/40R22 30.35 in (+2.31%)
• 295/30R22 28.97 in (−2.34%)
• 235/70R16 28.95 in (−2.39%)
• 215/85R16 30.39 in (+2.46%)
• 265/45R21 30.39 in (+2.46%)
• 305/35R22 30.41 in (+2.51%)
• 265/50R20 30.43 in (+2.60%)
• 235/75R15 28.88 in (−2.64%)
• 295/45R20 30.45 in (+2.67%)
• 245/75R16 30.47 in (+2.72%)
• 285/35R21 28.85 in (−2.72%)
• 265/55R19 30.48 in (+2.75%)
• 245/70R17 30.50 in (+2.84%)
• 265/60R18 30.52 in (+2.89%)
• 245/65R18 30.54 in (+2.96%)

Open 275/40R21 in the tire size calculator

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