225/45R18 tire size
225/45R18 is a metric size: 26.0" tall, 8.9" wide, on a 18" rim — about a 26x9.00R18. The sidewall is 4.0" and the tire turns 777 times per mile.
225/45R18 specs
| Overall diameter (height) | 25.97" · 660 mm |
|---|---|
| Section width | 8.86" · 225 mm |
| Sidewall height | 3.99" · 101 mm (45% of width) |
| Rim diameter | 18" |
| Circumference | 81.59" · 2.073 m |
| Revolutions per mile | 777 (483 per km) |
| Inch (flotation) equivalent | 26x9.00R18 |
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 | |
|---|---|---|---|---|---|
| 245/40R18 common | 25.72" | -0.99% | +20 mm | 59.4 mph | compare → |
| 225/40R18 common | 25.09" | -3.41% | 0 mm | 58.0 mph | compare → |
| 245/45R18 common | 26.68" | +2.73% | +20 mm | 61.6 mph | compare → |
| 235/50R18 common | 27.25" | +4.93% | +10 mm | 63.0 mph | compare → |
| 235/45R18 common | 26.33" | +1.36% | +10 mm | 60.8 mph | compare → |
| 235/40R18 common | 25.40" | -2.20% | +10 mm | 58.7 mph | compare → |
| 225/50R18 common | 26.86" | +3.41% | 0 mm | 62.0 mph | compare → |
| 255/35R18 common | 25.03" | -3.64% | +30 mm | 57.8 mph | compare → |
| 255/40R18 common | 26.03" | +0.23% | +30 mm | 60.1 mph | compare → |
| 275/35R18 common | 25.58" | -1.52% | +50 mm | 59.1 mph | compare → |
| 265/35R18 common | 25.30" | -2.58% | +40 mm | 58.5 mph | compare → |
| 255/45R18 common | 27.04" | +4.09% | +30 mm | 62.5 mph | compare → |
| 275/40R18 common | 26.66" | +2.65% | +50 mm | 61.6 mph | compare → |
| 215/45R18 common | 25.62" | -1.36% | -10 mm | 59.2 mph | compare → |
| 245/35R18 common | 24.75" | -4.70% | +20 mm | 57.2 mph | compare → |
| 215/40R18 | 24.77" | -4.62% | -10 mm | 57.2 mph | compare → |
| 285/35R18 | 25.85" | -0.45% | +60 mm | 59.7 mph | compare → |
| 265/40R18 | 26.35" | +1.44% | +40 mm | 60.9 mph | compare → |
| 295/30R18 | 24.97" | -3.87% | +70 mm | 57.7 mph | compare → |
| 315/30R18 | 25.44" | -2.05% | +90 mm | 58.8 mph | compare → |
| 285/30R18 | 24.73" | -4.77% | +60 mm | 57.1 mph | compare → |
| 295/35R18 | 26.13" | +0.61% | +70 mm | 60.4 mph | compare → |
| 335/30R18 | 25.91" | -0.23% | +110 mm | 59.9 mph | compare → |
| 215/50R18 | 26.46" | +1.89% | -10 mm | 61.1 mph | compare → |
| 285/40R18 | 26.98" | +3.87% | +60 mm | 62.3 mph | calculate → |
| 305/35R18 | 26.41" | +1.67% | +80 mm | 61.0 mph | calculate → |
| 145/70R18 | 25.99" | +0.08% | -80 mm | 60.0 mph | calculate → |
| 26x12.00R18 | 26.00" | +0.11% | +80 mm | 60.1 mph | calculate → |
| 26x6.00R18 | 26.00" | +0.11% | -73 mm | 60.1 mph | calculate → |
| 26x8.00R18 | 26.00" | +0.11% | -22 mm | 60.1 mph | calculate → |
| 155/70R18 | 26.54" | +2.20% | -70 mm | 61.3 mph | calculate → |
| 155/60R18 | 25.32" | -2.50% | -70 mm | 58.5 mph | calculate → |
| 305/30R18 | 25.20" | -2.96% | +80 mm | 58.2 mph | calculate → |
| 325/35R18 | 26.96" | +3.79% | +100 mm | 62.3 mph | calculate → |
| 165/70R18 | 27.09" | +4.32% | -60 mm | 62.6 mph | calculate → |
| 145/80R18 | 27.13" | +4.47% | -80 mm | 62.7 mph | calculate → |
| 345/30R18 | 26.15" | +0.68% | +120 mm | 60.4 mph | calculate → |
| 205/45R18 | 25.26" | -2.73% | -20 mm | 58.4 mph | calculate → |
| 315/35R18 | 26.68" | +2.73% | +90 mm | 61.6 mph | calculate → |
| 195/60R18 | 27.21" | +4.77% | -30 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 | |
|---|---|---|---|---|---|
| 225/50R17 common | 25.86" | -0.44% | 0 mm | 59.7 mph | compare → |
| 255/35R19 common | 26.03" | +0.21% | +30 mm | 60.1 mph | compare → |
| 245/35R19 common | 25.75" | -0.85% | +20 mm | 59.5 mph | compare → |
| 225/40R19 common | 26.09" | +0.44% | 0 mm | 60.3 mph | compare → |
| 285/30R19 | 25.73" | -0.92% | +60 mm | 59.4 mph | compare → |
| 205/55R17 | 25.88" | -0.36% | -20 mm | 59.8 mph | compare → |
| 305/30R19 | 26.20" | +0.89% | +80 mm | 60.5 mph | compare → |
| 295/30R19 | 25.97" | -0.02% | +70 mm | 60.0 mph | compare → |
| 255/45R17 | 26.04" | +0.24% | +30 mm | 60.1 mph | compare → |
| 285/40R17 | 25.98" | +0.02% | +60 mm | 60.0 mph | calculate → |
| 195/60R17 | 26.21" | +0.92% | -30 mm | 60.6 mph | calculate → |
| 175/65R17 | 25.96" | -0.06% | -50 mm | 60.0 mph | calculate → |
| 145/80R17 | 26.13" | +0.62% | -80 mm | 60.4 mph | calculate → |
| 26x6.00R17 | 26.00" | +0.11% | -73 mm | 60.1 mph | calculate → |
| 185/60R17 | 25.74" | -0.89% | -40 mm | 59.5 mph | calculate → |
| 165/70R17 | 26.09" | +0.47% | -60 mm | 60.3 mph | calculate → |
Try another size against 225/45R18
Questions
What size is 225/45R18 in inches?
225/45R18 is about 26.0" tall and 8.9" wide on a 18-inch rim — roughly a 26x9.00R18 in inch sizing.
What does 225/45R18 mean?
225 mm section width, sidewall 45% of the width (3.99"), radial construction, 18-inch rim.
What tire sizes are equivalent to 225/45R18?
On the same 18" rim, within 3% of the diameter: 145/70R18 (+0.08%), 26x12.00R18 (+0.11%), 26x6.00R18 (+0.11%), 26x8.00R18 (+0.11%), 255/40R18 (+0.23%), 335/30R18 (-0.23%).
How many revolutions per mile does a 225/45R18 tire make?
About 777 revolutions per mile (circumference 81.6").
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.