285/40R18 tire size
285/40R18 is a metric size: 27.0" tall, 11.2" wide, on a 18" rim — about a 27x11.00R18. The sidewall is 4.5" and the tire turns 748 times per mile.
285/40R18 specs
| Overall diameter (height) | 26.98" · 685 mm |
|---|---|
| Section width | 11.22" · 285 mm |
| Sidewall height | 4.49" · 114 mm (40% of width) |
| Rim diameter | 18" |
| Circumference | 84.75" · 2.153 m |
| Revolutions per mile | 748 (465 per km) |
| Inch (flotation) equivalent | 27x11.00R18 |
Equivalent sizes on a 18" rim
Sizes within ±5% of the overall diameter. Green rows are inside the usual ±3% limit for keeping the speedometer, ABS and gearing right; red rows are bigger changes that need clearance checks.
| Size | Diameter | Difference | Width | Speedo at 60 | |
|---|---|---|---|---|---|
| 225/45R18 common | 25.97" | -3.72% | -60 mm | 57.8 mph | calculate → |
| 245/40R18 common | 25.72" | -4.67% | -40 mm | 57.2 mph | calculate → |
| 245/45R18 common | 26.68" | -1.09% | -40 mm | 59.3 mph | calculate → |
| 235/50R18 common | 27.25" | +1.02% | -50 mm | 60.6 mph | calculate → |
| 235/45R18 common | 26.33" | -2.41% | -50 mm | 58.6 mph | calculate → |
| 235/55R18 common | 28.18" | +4.45% | -50 mm | 62.7 mph | calculate → |
| 225/50R18 common | 26.86" | -0.44% | -60 mm | 59.7 mph | calculate → |
| 225/55R18 common | 27.74" | +2.85% | -60 mm | 61.7 mph | calculate → |
| 255/40R18 common | 26.03" | -3.50% | -30 mm | 57.9 mph | calculate → |
| 245/50R18 common | 27.65" | +2.48% | -40 mm | 61.5 mph | calculate → |
| 255/45R18 common | 27.04" | +0.22% | -30 mm | 60.1 mph | calculate → |
| 215/55R18 common | 27.31" | +1.24% | -70 mm | 60.7 mph | calculate → |
| 275/40R18 common | 26.66" | -1.17% | -10 mm | 59.3 mph | calculate → |
| 265/40R18 | 26.35" | -2.34% | -20 mm | 58.6 mph | calculate → |
| 285/35R18 | 25.85" | -4.16% | 0 mm | 57.5 mph | calculate → |
| 295/35R18 | 26.13" | -3.14% | +10 mm | 58.1 mph | calculate → |
| 335/30R18 | 25.91" | -3.94% | +50 mm | 57.6 mph | calculate → |
| 275/45R18 | 27.74" | +2.85% | -10 mm | 61.7 mph | calculate → |
| 215/50R18 | 26.46" | -1.90% | -70 mm | 58.9 mph | calculate → |
| 295/40R18 | 27.29" | +1.17% | +10 mm | 60.7 mph | calculate → |
| 265/45R18 | 27.39" | +1.53% | -20 mm | 60.9 mph | calculate → |
| 345/35R18 | 27.51" | +1.97% | +60 mm | 61.2 mph | calculate → |
| 305/35R18 | 26.41" | -2.12% | +20 mm | 58.7 mph | calculate → |
| 255/50R18 | 28.04" | +3.94% | -30 mm | 62.4 mph | calculate → |
| 315/40R18 | 27.92" | +3.50% | +30 mm | 62.1 mph | calculate → |
| 305/40R18 | 27.61" | +2.34% | +20 mm | 61.4 mph | calculate → |
| 215/60R18 | 28.16" | +4.38% | -70 mm | 62.6 mph | calculate → |
| 325/35R18 | 26.96" | -0.07% | +40 mm | 60.0 mph | calculate → |
| 165/70R18 | 27.09" | +0.44% | -120 mm | 60.3 mph | calculate → |
| 145/80R18 | 27.13" | +0.58% | -140 mm | 60.4 mph | calculate → |
| 155/70R18 | 26.54" | -1.61% | -130 mm | 59.0 mph | calculate → |
| 145/85R18 | 27.70" | +2.70% | -140 mm | 61.6 mph | calculate → |
| 26x12.00R18 | 26.00" | -3.62% | +20 mm | 57.8 mph | calculate → |
| 26x6.00R18 | 26.00" | -3.62% | -133 mm | 57.8 mph | calculate → |
| 26x8.00R18 | 26.00" | -3.62% | -82 mm | 57.8 mph | calculate → |
| 145/70R18 | 25.99" | -3.65% | -140 mm | 57.8 mph | calculate → |
| 28x12.00R18 | 28.00" | +3.79% | +20 mm | 62.3 mph | calculate → |
| 285/45R18 | 28.10" | +4.16% | 0 mm | 62.5 mph | calculate → |
| 195/60R18 | 27.21" | +0.88% | -90 mm | 60.5 mph | calculate → |
| 315/35R18 | 26.68" | -1.09% | +30 mm | 59.3 mph | calculate → |
| 205/60R18 | 27.69" | +2.63% | -80 mm | 61.6 mph | calculate → |
| 345/30R18 | 26.15" | -3.06% | +60 mm | 58.2 mph | calculate → |
| 28x10.00R18 | 28.00" | +3.79% | -31 mm | 62.3 mph | calculate → |
Plus / minus sizing: 17" and 19" rims
Same overall height on a different rim. Check wheel width and clearance before switching.
| Size | Diameter | Difference | Width | Speedo at 60 | |
|---|---|---|---|---|---|
| 225/55R17 common | 26.74" | -0.86% | -60 mm | 59.5 mph | calculate → |
| 245/40R19 common | 26.72" | -0.96% | -40 mm | 59.4 mph | calculate → |
| 235/55R17 common | 27.18" | +0.74% | -50 mm | 60.4 mph | calculate → |
| 255/40R19 common | 27.03" | +0.20% | -30 mm | 60.1 mph | calculate → |
| 215/60R17 common | 27.16" | +0.67% | -70 mm | 60.4 mph | calculate → |
| 225/45R19 common | 26.97" | -0.01% | -60 mm | 60.0 mph | calculate → |
| 285/35R19 common | 26.85" | -0.45% | 0 mm | 59.7 mph | calculate → |
| 295/35R19 | 27.13" | +0.57% | +10 mm | 60.3 mph | calculate → |
| 345/30R19 | 27.15" | +0.64% | +60 mm | 60.4 mph | calculate → |
| 255/50R17 | 27.04" | +0.23% | -30 mm | 60.1 mph | calculate → |
| 155/80R17 | 26.76" | -0.79% | -130 mm | 59.5 mph | calculate → |
| 335/30R19 | 26.91" | -0.23% | +50 mm | 59.9 mph | calculate → |
Try another size against 285/40R18
Questions
What size is 285/40R18 in inches?
285/40R18 is about 27.0" tall and 11.2" wide on a 18-inch rim — roughly a 27x11.00R18 in inch sizing.
What does 285/40R18 mean?
285 mm section width, sidewall 40% of the width (4.49"), radial construction, 18-inch rim.
What tire sizes are equivalent to 285/40R18?
On the same 18" rim, within 3% of the diameter: 325/35R18 (-0.07%), 255/45R18 (+0.22%), 225/50R18 (-0.44%), 165/70R18 (+0.44%), 145/80R18 (+0.58%), 195/60R18 (+0.88%).
How many revolutions per mile does a 285/40R18 tire make?
About 748 revolutions per mile (circumference 84.7").
How these numbers are computed
Diameter = rim + 2 × sidewall, sidewall = width × aspect ÷ 100, circumference = π × diameter, revolutions per mile = 63,360 ÷ circumference. Real tires differ by brand by a few tenths of an inch. Last reviewed October 14, 2026.