215/45R18 tire size
215/45R18 is a metric size: 25.6" tall, 8.5" wide, on a 18" rim — about a 25.5x8.50R18. The sidewall is 3.8" and the tire turns 787 times per mile.
215/45R18 specs
| Overall diameter (height) | 25.62" · 651 mm |
|---|---|
| Section width | 8.46" · 215 mm |
| Sidewall height | 3.81" · 97 mm (45% of width) |
| Rim diameter | 18" |
| Circumference | 80.48" · 2.044 m |
| Revolutions per mile | 787 (489 per km) |
| Inch (flotation) equivalent | 25.5x8.50R18 |
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 | |
|---|---|---|---|---|---|
| 245/40R18 common | 25.72" | +0.38% | +30 mm | 60.2 mph | compare → |
| 225/45R18 common | 25.97" | +1.38% | +10 mm | 60.8 mph | compare → |
| 225/40R18 common | 25.09" | -2.07% | +10 mm | 58.8 mph | compare → |
| 245/45R18 common | 26.68" | +4.15% | +30 mm | 62.5 mph | compare → |
| 235/45R18 common | 26.33" | +2.77% | +20 mm | 61.7 mph | compare → |
| 235/40R18 common | 25.40" | -0.85% | +20 mm | 59.5 mph | compare → |
| 225/50R18 common | 26.86" | +4.84% | +10 mm | 62.9 mph | compare → |
| 255/35R18 common | 25.03" | -2.31% | +40 mm | 58.6 mph | compare → |
| 255/40R18 common | 26.03" | +1.61% | +40 mm | 61.0 mph | compare → |
| 275/35R18 common | 25.58" | -0.15% | +60 mm | 59.9 mph | compare → |
| 265/35R18 common | 25.30" | -1.23% | +50 mm | 59.3 mph | compare → |
| 275/40R18 common | 26.66" | +4.07% | +60 mm | 62.4 mph | compare → |
| 245/35R18 common | 24.75" | -3.38% | +30 mm | 58.0 mph | compare → |
| 215/40R18 | 24.77" | -3.30% | 0 mm | 58.0 mph | compare → |
| 285/35R18 | 25.85" | +0.92% | +70 mm | 60.6 mph | compare → |
| 265/40R18 | 26.35" | +2.84% | +50 mm | 61.7 mph | compare → |
| 295/30R18 | 24.97" | -2.54% | +80 mm | 58.5 mph | compare → |
| 315/30R18 | 25.44" | -0.69% | +100 mm | 59.6 mph | compare → |
| 285/30R18 | 24.73" | -3.46% | +70 mm | 57.9 mph | compare → |
| 295/35R18 | 26.13" | +2.00% | +80 mm | 61.2 mph | compare → |
| 205/40R18 | 24.46" | -4.53% | -10 mm | 57.3 mph | compare → |
| 335/30R18 | 25.91" | +1.15% | +120 mm | 60.7 mph | compare → |
| 215/50R18 | 26.46" | +3.30% | 0 mm | 62.0 mph | compare → |
| 305/35R18 | 26.41" | +3.07% | +90 mm | 61.8 mph | calculate → |
| 235/35R18 | 24.48" | -4.46% | +20 mm | 57.3 mph | calculate → |
| 155/60R18 | 25.32" | -1.15% | -60 mm | 59.3 mph | calculate → |
| 145/70R18 | 25.99" | +1.46% | -70 mm | 60.9 mph | calculate → |
| 26x12.00R18 | 26.00" | +1.49% | +90 mm | 60.9 mph | calculate → |
| 26x6.00R18 | 26.00" | +1.49% | -63 mm | 60.9 mph | calculate → |
| 26x8.00R18 | 26.00" | +1.49% | -12 mm | 60.9 mph | calculate → |
| 305/30R18 | 25.20" | -1.61% | +90 mm | 59.0 mph | calculate → |
| 155/70R18 | 26.54" | +3.61% | -60 mm | 62.2 mph | calculate → |
| 205/45R18 | 25.26" | -1.38% | -10 mm | 59.2 mph | calculate → |
| 345/30R18 | 26.15" | +2.07% | +130 mm | 61.2 mph | calculate → |
| 315/35R18 | 26.68" | +4.15% | +100 mm | 62.5 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" | +0.94% | +10 mm | 60.6 mph | compare → |
| 215/50R17 common | 25.46" | -0.60% | 0 mm | 59.6 mph | compare → |
| 245/45R17 common | 25.68" | +0.25% | +30 mm | 60.1 mph | compare → |
| 245/35R19 common | 25.75" | +0.52% | +30 mm | 60.3 mph | compare → |
| 235/35R19 common | 25.48" | -0.55% | +20 mm | 59.7 mph | compare → |
| 285/30R19 | 25.73" | +0.45% | +70 mm | 60.3 mph | compare → |
| 275/40R17 | 25.66" | +0.17% | +60 mm | 60.1 mph | compare → |
| 275/30R19 | 25.50" | -0.48% | +60 mm | 59.7 mph | compare → |
| 315/35R17 | 25.68" | +0.25% | +100 mm | 60.1 mph | compare → |
| 155/70R17 | 25.54" | -0.29% | -60 mm | 59.8 mph | calculate → |
| 185/60R17 | 25.74" | +0.48% | -30 mm | 60.3 mph | calculate → |
Try another size against 215/45R18
Questions
What size is 215/45R18 in inches?
215/45R18 is about 25.6" tall and 8.5" wide on a 18-inch rim — roughly a 25.5x8.50R18 in inch sizing.
What does 215/45R18 mean?
215 mm section width, sidewall 45% of the width (3.81"), radial construction, 18-inch rim.
What tire sizes are equivalent to 215/45R18?
On the same 18" rim, within 3% of the diameter: 275/35R18 (-0.15%), 245/40R18 (+0.38%), 315/30R18 (-0.69%), 235/40R18 (-0.85%), 285/35R18 (+0.92%), 335/30R18 (+1.15%).
How many revolutions per mile does a 215/45R18 tire make?
About 787 revolutions per mile (circumference 80.5").
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.