145/80R18 tire size
145/80R18 is a metric size: 27.1" tall, 5.7" wide, on a 18" rim — about a 27x5.50R18. The sidewall is 4.6" and the tire turns 743 times per mile.
145/80R18 specs
| Overall diameter (height) | 27.13" · 689 mm |
|---|---|
| Section width | 5.71" · 145 mm |
| Sidewall height | 4.57" · 116 mm (80% of width) |
| Rim diameter | 18" |
| Circumference | 85.24" · 2.165 m |
| Revolutions per mile | 743 (462 per km) |
| Inch (flotation) equivalent | 27x5.50R18 |
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" | -4.28% | +80 mm | 57.4 mph | calculate → |
| 245/45R18 common | 26.68" | -1.67% | +100 mm | 59.0 mph | calculate → |
| 235/50R18 common | 27.25" | +0.44% | +90 mm | 60.3 mph | calculate → |
| 235/45R18 common | 26.33" | -2.97% | +90 mm | 58.2 mph | calculate → |
| 235/55R18 common | 28.18" | +3.85% | +90 mm | 62.3 mph | calculate → |
| 225/50R18 common | 26.86" | -1.02% | +80 mm | 59.4 mph | calculate → |
| 225/55R18 common | 27.74" | +2.25% | +80 mm | 61.3 mph | calculate → |
| 255/40R18 common | 26.03" | -4.06% | +110 mm | 57.6 mph | calculate → |
| 245/50R18 common | 27.65" | +1.89% | +100 mm | 61.1 mph | calculate → |
| 255/45R18 common | 27.04" | -0.36% | +110 mm | 59.8 mph | calculate → |
| 215/55R18 common | 27.31" | +0.65% | +70 mm | 60.4 mph | calculate → |
| 275/40R18 common | 26.66" | -1.74% | +130 mm | 59.0 mph | calculate → |
| 265/40R18 | 26.35" | -2.90% | +120 mm | 58.3 mph | calculate → |
| 285/35R18 | 25.85" | -4.72% | +140 mm | 57.2 mph | calculate → |
| 295/35R18 | 26.13" | -3.70% | +150 mm | 57.8 mph | calculate → |
| 335/30R18 | 25.91" | -4.50% | +190 mm | 57.3 mph | calculate → |
| 275/45R18 | 27.74" | +2.25% | +130 mm | 61.3 mph | calculate → |
| 215/50R18 | 26.46" | -2.47% | +70 mm | 58.5 mph | calculate → |
| 295/40R18 | 27.29" | +0.58% | +150 mm | 60.3 mph | calculate → |
| 265/45R18 | 27.39" | +0.94% | +120 mm | 60.6 mph | calculate → |
| 285/40R18 | 26.98" | -0.58% | +140 mm | 59.7 mph | calculate → |
| 345/35R18 | 27.51" | +1.38% | +200 mm | 60.8 mph | calculate → |
| 305/35R18 | 26.41" | -2.68% | +160 mm | 58.4 mph | calculate → |
| 295/45R18 | 28.45" | +4.86% | +150 mm | 62.9 mph | calculate → |
| 255/50R18 | 28.04" | +3.34% | +110 mm | 62.0 mph | calculate → |
| 315/40R18 | 27.92" | +2.90% | +170 mm | 61.7 mph | calculate → |
| 305/40R18 | 27.61" | +1.74% | +160 mm | 61.0 mph | calculate → |
| 215/60R18 | 28.16" | +3.77% | +70 mm | 62.3 mph | calculate → |
| 155/85R18 | 28.37" | +4.57% | +10 mm | 62.7 mph | calculate → |
| 165/70R18 | 27.09" | -0.15% | +20 mm | 59.9 mph | calculate → |
| 325/35R18 | 26.96" | -0.65% | +180 mm | 59.6 mph | calculate → |
| 145/85R18 | 27.70" | +2.10% | 0 mm | 61.3 mph | calculate → |
| 155/70R18 | 26.54" | -2.18% | +10 mm | 58.7 mph | calculate → |
| 28x12.00R18 | 28.00" | +3.19% | +160 mm | 61.9 mph | calculate → |
| 285/45R18 | 28.10" | +3.55% | +140 mm | 62.1 mph | calculate → |
| 26x12.00R18 | 26.00" | -4.18% | +160 mm | 57.5 mph | calculate → |
| 26x6.00R18 | 26.00" | -4.18% | +7 mm | 57.5 mph | calculate → |
| 26x8.00R18 | 26.00" | -4.18% | +58 mm | 57.5 mph | calculate → |
| 145/70R18 | 25.99" | -4.21% | 0 mm | 57.5 mph | calculate → |
| 195/60R18 | 27.21" | +0.29% | +50 mm | 60.2 mph | calculate → |
| 315/35R18 | 26.68" | -1.67% | +170 mm | 59.0 mph | calculate → |
| 205/60R18 | 27.69" | +2.03% | +60 mm | 61.2 mph | calculate → |
| 28x10.00R18 | 28.00" | +3.19% | +109 mm | 61.9 mph | calculate → |
| 345/30R18 | 26.15" | -3.63% | +200 mm | 57.8 mph | calculate → |
| 265/50R18 | 28.43" | +4.79% | +120 mm | 62.9 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 | |
|---|---|---|---|---|---|
| 235/55R17 common | 27.18" | +0.16% | +90 mm | 60.1 mph | calculate → |
| 255/40R19 common | 27.03" | -0.38% | +110 mm | 59.8 mph | calculate → |
| 215/60R17 common | 27.16" | +0.09% | +70 mm | 60.1 mph | calculate → |
| 225/45R19 common | 26.97" | -0.59% | +80 mm | 59.6 mph | calculate → |
| 235/45R19 common | 27.33" | +0.71% | +90 mm | 60.4 mph | calculate → |
| 265/40R19 | 27.35" | +0.78% | +120 mm | 60.5 mph | calculate → |
| 295/35R19 | 27.13" | -0.01% | +150 mm | 60.0 mph | calculate → |
| 345/30R19 | 27.15" | +0.06% | +200 mm | 60.0 mph | calculate → |
| 355/30R19 | 27.39" | +0.93% | +210 mm | 60.6 mph | calculate → |
| 255/50R17 | 27.04" | -0.35% | +110 mm | 59.8 mph | calculate → |
| 165/80R17 | 27.39" | +0.96% | +20 mm | 60.6 mph | calculate → |
| 175/60R19 | 27.27" | +0.49% | +30 mm | 60.3 mph | calculate → |
| 145/90R17 | 27.28" | +0.52% | 0 mm | 60.3 mph | calculate → |
| 335/30R19 | 26.91" | -0.81% | +190 mm | 59.5 mph | calculate → |
Try another size against 145/80R18
Questions
What size is 145/80R18 in inches?
145/80R18 is about 27.1" tall and 5.7" wide on a 18-inch rim — roughly a 27x5.50R18 in inch sizing.
What does 145/80R18 mean?
145 mm section width, sidewall 80% of the width (4.57"), radial construction, 18-inch rim.
What tire sizes are equivalent to 145/80R18?
On the same 18" rim, within 3% of the diameter: 165/70R18 (-0.15%), 195/60R18 (+0.29%), 255/45R18 (-0.36%), 235/50R18 (+0.44%), 285/40R18 (-0.58%), 295/40R18 (+0.58%).
How many revolutions per mile does a 145/80R18 tire make?
About 743 revolutions per mile (circumference 85.2").
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.