235/40R18 tire size

A 235/40R18 tire is 25.40 in (645.2 mm) tall and 9.25 in (235.0 mm) wide, and turns 794 revolutions per mile.

• 25.40 inOverall diameter
• 3.70 inSidewall height
• 794Revolutions per mile
• 25.4x9.3R18Flotation equivalent

235/40R18 is a 18-inch tire with a 235 mm (9.25 in) section width and a 40% aspect ratio, giving a 3.70-inch sidewall and a flotation-style size of about 25.4x9.3R18.

Its overall diameter is 25.40 inches, so it rolls 79.8 inches per revolution and turns about 794 times per mile.

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

Compare 235/40R18 with plausible swaps

• 195/60R16 vs 235/40R18 (−0.74%)
• 215/55R16 vs 235/40R18 (−0.36%)
• 235/45R17 vs 235/40R18 (−0.29%)
• 265/40R17 vs 235/40R18 (−0.22%)
• 215/50R17 vs 235/40R18 (+0.25%)
• 275/40R17 vs 235/40R18 (+1.02%)
• 235/35R18 vs 235/40R18 (−3.64%)
• 215/40R18 vs 235/40R18 (−2.48%)
• 225/40R18 vs 235/40R18 (−1.24%)
• 265/35R18 vs 235/40R18 (−0.39%)
• 235/40R18 vs 275/35R18 (+0.70%)
• 235/40R18 vs 215/45R18 (+0.85%)
• 235/40R18 vs 245/40R18 (+1.24%)
• 235/40R18 vs 255/40R18 (+2.48%)
• 235/40R18 vs 235/45R18 (+3.64%)
• 235/40R18 vs 225/35R19 (−0.79%)
• 235/40R18 vs 265/30R19 (−0.56%)
• 235/40R18 vs 235/35R19 (+0.29%)
• 235/40R18 vs 275/30R19 (+0.37%)
• 235/40R18 vs 225/30R20 (−0.34%)

Sizes within 3% of 25.40 in diameter

• 265/40R17 25.35 in (−0.22%)
• 215/50R17 25.46 in (+0.25%)
• 235/35R19 25.48 in (+0.29%)
• 235/45R17 25.33 in (−0.29%)
• 225/30R20 25.31 in (−0.34%)
• 205/65R15 25.49 in (+0.36%)
• 215/55R16 25.31 in (−0.36%)
• 275/30R19 25.50 in (+0.37%)
• 265/35R18 25.30 in (−0.39%)
• 205/70R14 25.30 in (−0.40%)
• 195/75R14 25.52 in (+0.45%)
• 265/30R19 25.26 in (−0.56%)
• 275/35R18 25.58 in (+0.70%)
• 195/60R16 25.21 in (−0.74%)
• 225/35R19 25.20 in (−0.79%)
• 215/45R18 25.62 in (+0.85%)
• 225/60R15 25.63 in (+0.90%)
• 215/60R15 25.16 in (−0.96%)
• 275/40R17 25.66 in (+1.02%)
• 245/45R17 25.68 in (+1.10%)
• 205/60R16 25.69 in (+1.12%)
• 225/40R18 25.09 in (−1.24%)
• 245/40R18 25.72 in (+1.24%)
• 285/30R19 25.73 in (+1.30%)
• 205/50R17 25.07 in (−1.30%)
• 225/55R16 25.74 in (+1.35%)
• 195/70R15 25.75 in (+1.36%)
• 245/35R19 25.75 in (+1.38%)
• 255/40R17 25.03 in (−1.46%)
• 255/35R18 25.03 in (−1.47%)
• 255/30R19 25.02 in (−1.49%)
• 195/65R15 24.98 in (−1.66%)
• 225/45R17 24.97 in (−1.69%)
• 215/70R14 25.85 in (+1.77%)
• 285/35R18 25.85 in (+1.78%)
• 225/50R17 25.86 in (+1.80%)
• 205/55R17 25.88 in (+1.88%)
• 205/55R16 24.88 in (−2.06%)
• 225/50R16 24.86 in (−2.14%)
• 295/30R19 25.97 in (+2.23%)
• 225/45R18 25.97 in (+2.25%)
• 215/65R15 26.00 in (+2.37%)
• 245/30R19 24.79 in (−2.42%)
• 255/30R20 26.02 in (+2.45%)
• 255/35R19 26.03 in (+2.46%)
• 215/40R18 24.77 in (−2.48%)
• 255/40R18 26.03 in (+2.48%)
• 255/45R17 26.04 in (+2.50%)
• 245/35R18 24.75 in (−2.56%)
• 195/70R14 24.75 in (−2.57%)
• 185/60R16 24.74 in (−2.60%)
• 225/40R19 26.09 in (+2.70%)
• 245/40R17 24.72 in (−2.70%)
• 235/60R15 26.10 in (+2.76%)
• 205/75R14 26.11 in (+2.77%)
• 205/60R15 24.69 in (−2.82%)
• 295/35R18 26.13 in (+2.87%)
• 215/60R16 26.16 in (+2.98%)

Open 235/40R18 in the tire size calculator

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