245/45R18 tire size
245/45R18 is a metric size: 26.7" tall, 9.6" wide, on a 18" rim — about a 26.5x9.50R18. The sidewall is 4.3" and the tire turns 756 times per mile.
245/45R18 specs
| Overall diameter (height) | 26.68" · 678 mm |
|---|---|
| Section width | 9.65" · 245 mm |
| Sidewall height | 4.34" · 110 mm (45% of width) |
| Rim diameter | 18" |
| Circumference | 83.82" · 2.129 m |
| Revolutions per mile | 756 (470 per km) |
| Inch (flotation) equivalent | 26.5x9.50R18 |
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" | -2.66% | -20 mm | 58.4 mph | compare → |
| 245/40R18 common | 25.72" | -3.62% | 0 mm | 57.8 mph | compare → |
| 235/50R18 common | 27.25" | +2.14% | -10 mm | 61.3 mph | compare → |
| 235/45R18 common | 26.33" | -1.33% | -10 mm | 59.2 mph | compare → |
| 235/40R18 common | 25.40" | -4.80% | -10 mm | 57.1 mph | compare → |
| 225/50R18 common | 26.86" | +0.66% | -20 mm | 60.4 mph | compare → |
| 225/55R18 common | 27.74" | +3.98% | -20 mm | 62.4 mph | compare → |
| 255/40R18 common | 26.03" | -2.43% | +10 mm | 58.5 mph | compare → |
| 245/50R18 common | 27.65" | +3.62% | 0 mm | 62.2 mph | compare → |
| 275/35R18 common | 25.58" | -4.13% | +30 mm | 57.5 mph | compare → |
| 255/45R18 common | 27.04" | +1.33% | +10 mm | 60.8 mph | compare → |
| 215/55R18 common | 27.31" | +2.36% | -30 mm | 61.4 mph | compare → |
| 275/40R18 common | 26.66" | -0.07% | +30 mm | 60.0 mph | compare → |
| 215/45R18 common | 25.62" | -3.98% | -30 mm | 57.6 mph | compare → |
| 265/40R18 | 26.35" | -1.25% | +20 mm | 59.2 mph | compare → |
| 285/35R18 | 25.85" | -3.10% | +40 mm | 58.1 mph | compare → |
| 315/30R18 | 25.44" | -4.65% | +70 mm | 57.2 mph | compare → |
| 295/35R18 | 26.13" | -2.07% | +50 mm | 58.8 mph | compare → |
| 335/30R18 | 25.91" | -2.88% | +90 mm | 58.3 mph | compare → |
| 275/45R18 | 27.74" | +3.98% | +30 mm | 62.4 mph | compare → |
| 215/50R18 | 26.46" | -0.81% | -30 mm | 59.5 mph | compare → |
| 295/40R18 | 27.29" | +2.29% | +50 mm | 61.4 mph | compare → |
| 265/45R18 | 27.39" | +2.66% | +20 mm | 61.6 mph | compare → |
| 285/40R18 | 26.98" | +1.11% | +40 mm | 60.7 mph | calculate → |
| 305/35R18 | 26.41" | -1.03% | +60 mm | 59.4 mph | calculate → |
| 345/35R18 | 27.51" | +3.10% | +100 mm | 61.9 mph | calculate → |
| 315/40R18 | 27.92" | +4.65% | +70 mm | 62.8 mph | calculate → |
| 305/40R18 | 27.61" | +3.47% | +60 mm | 62.1 mph | calculate → |
| 155/70R18 | 26.54" | -0.52% | -90 mm | 59.7 mph | calculate → |
| 325/35R18 | 26.96" | +1.03% | +80 mm | 60.6 mph | calculate → |
| 165/70R18 | 27.09" | +1.55% | -80 mm | 60.9 mph | calculate → |
| 145/80R18 | 27.13" | +1.70% | -100 mm | 61.0 mph | calculate → |
| 26x12.00R18 | 26.00" | -2.55% | +60 mm | 58.5 mph | calculate → |
| 26x6.00R18 | 26.00" | -2.55% | -93 mm | 58.5 mph | calculate → |
| 26x8.00R18 | 26.00" | -2.55% | -42 mm | 58.5 mph | calculate → |
| 145/70R18 | 25.99" | -2.58% | -100 mm | 58.5 mph | calculate → |
| 145/85R18 | 27.70" | +3.84% | -100 mm | 62.3 mph | calculate → |
| 28x12.00R18 | 28.00" | +4.94% | +60 mm | 63.0 mph | calculate → |
| 315/35R18 | 26.68" | 0.00% | +70 mm | 60.0 mph | calculate → |
| 195/60R18 | 27.21" | +1.99% | -50 mm | 61.2 mph | calculate → |
| 345/30R18 | 26.15" | -1.99% | +100 mm | 58.8 mph | calculate → |
| 205/60R18 | 27.69" | +3.76% | -40 mm | 62.3 mph | calculate → |
| 28x10.00R18 | 28.00" | +4.94% | +9 mm | 63.0 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" | +0.24% | -20 mm | 60.1 mph | compare → |
| 245/40R19 common | 26.72" | +0.13% | 0 mm | 60.1 mph | compare → |
| 275/35R19 common | 26.58" | -0.38% | +30 mm | 59.8 mph | compare → |
| 285/35R19 common | 26.85" | +0.65% | +40 mm | 60.4 mph | compare → |
| 325/30R19 | 26.68" | -0.01% | +80 mm | 60.0 mph | compare → |
| 245/50R17 | 26.65" | -0.13% | 0 mm | 59.9 mph | compare → |
| 315/30R19 | 26.44" | -0.90% | +70 mm | 59.5 mph | compare → |
| 195/50R19 | 26.68" | -0.01% | -50 mm | 60.0 mph | calculate → |
| 155/80R17 | 26.76" | +0.31% | -90 mm | 60.2 mph | calculate → |
| 335/30R19 | 26.91" | +0.87% | +90 mm | 60.5 mph | calculate → |
| 205/60R17 | 26.69" | +0.01% | -40 mm | 60.0 mph | calculate → |
Try another size against 245/45R18
Questions
What size is 245/45R18 in inches?
245/45R18 is about 26.7" tall and 9.6" wide on a 18-inch rim — roughly a 26.5x9.50R18 in inch sizing.
What does 245/45R18 mean?
245 mm section width, sidewall 45% of the width (4.34"), radial construction, 18-inch rim.
What tire sizes are equivalent to 245/45R18?
On the same 18" rim, within 3% of the diameter: 315/35R18 (0.00%), 275/40R18 (-0.07%), 155/70R18 (-0.52%), 225/50R18 (+0.66%), 215/50R18 (-0.81%), 305/35R18 (-1.03%).
How many revolutions per mile does a 245/45R18 tire make?
About 756 revolutions per mile (circumference 83.8").
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.