325/45R18 tire size
325/45R18 is a metric size: 29.5" tall, 12.8" wide, on a 18" rim — about a 29.5x13.00R18. The sidewall is 5.8" and the tire turns 683 times per mile.
325/45R18 specs
| Overall diameter (height) | 29.52" · 750 mm |
|---|---|
| Section width | 12.80" · 325 mm |
| Sidewall height | 5.76" · 146 mm (45% of width) |
| Rim diameter | 18" |
| Circumference | 92.73" · 2.355 m |
| Revolutions per mile | 683 (425 per km) |
| Inch (flotation) equivalent | 29.5x13.00R18 |
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 | |
|---|---|---|---|---|---|
| 235/60R18 common | 29.10" | -1.40% | -90 mm | 59.2 mph | calculate → |
| 235/55R18 common | 28.18" | -4.54% | -90 mm | 57.3 mph | calculate → |
| 265/60R18 common | 30.52" | +3.40% | -60 mm | 62.0 mph | calculate → |
| 225/60R18 common | 28.63" | -3.00% | -100 mm | 58.2 mph | calculate → |
| 245/60R18 common | 29.57" | +0.20% | -80 mm | 60.1 mph | calculate → |
| 255/55R18 common | 29.04" | -1.60% | -70 mm | 59.0 mph | calculate → |
| 235/65R18 common | 30.03" | +1.73% | -90 mm | 61.0 mph | calculate → |
| 255/60R18 | 30.05" | +1.80% | -70 mm | 61.1 mph | calculate → |
| 245/55R18 | 28.61" | -3.07% | -80 mm | 58.2 mph | calculate → |
| 295/45R18 | 28.45" | -3.60% | -30 mm | 57.8 mph | calculate → |
| 155/90R18 | 28.98" | -1.80% | -170 mm | 58.9 mph | calculate → |
| 165/90R18 | 29.69" | +0.60% | -160 mm | 60.4 mph | calculate → |
| 285/50R18 | 29.22" | -1.00% | -40 mm | 59.4 mph | calculate → |
| 305/45R18 | 28.81" | -2.40% | -20 mm | 58.6 mph | calculate → |
| 155/85R18 | 28.37" | -3.87% | -170 mm | 57.7 mph | calculate → |
| 215/60R18 | 28.16" | -4.60% | -110 mm | 57.2 mph | calculate → |
| 275/55R18 | 29.91" | +1.33% | -50 mm | 60.8 mph | calculate → |
| 285/55R18 | 30.34" | +2.80% | -40 mm | 61.7 mph | calculate → |
| 175/90R18 | 30.40" | +3.00% | -150 mm | 61.8 mph | calculate → |
| 245/65R18 | 30.54" | +3.47% | -80 mm | 62.1 mph | calculate → |
| 285/45R18 | 28.10" | -4.80% | -40 mm | 57.1 mph | calculate → |
| 235/70R18 | 30.95" | +4.87% | -90 mm | 62.9 mph | calculate → |
| 225/65R18 | 29.52" | 0.00% | -100 mm | 60.0 mph | calculate → |
| 265/55R18 | 29.48" | -0.13% | -60 mm | 59.9 mph | calculate → |
| 265/50R18 | 28.43" | -3.67% | -60 mm | 57.8 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 | |
|---|---|---|---|---|---|
| 245/65R17 common | 29.54" | +0.08% | -80 mm | 60.0 mph | calculate → |
| 245/55R19 common | 29.61" | +0.32% | -80 mm | 60.2 mph | calculate → |
| 265/50R19 common | 29.43" | -0.28% | -60 mm | 59.8 mph | calculate → |
| 265/60R17 | 29.52" | +0.01% | -60 mm | 60.0 mph | calculate → |
| 295/45R19 | 29.45" | -0.21% | -30 mm | 59.9 mph | calculate → |
| 175/90R17 | 29.40" | -0.39% | -150 mm | 59.8 mph | calculate → |
| 225/70R17 | 29.40" | -0.39% | -100 mm | 59.8 mph | calculate → |
Try another size against 325/45R18
Questions
What size is 325/45R18 in inches?
325/45R18 is about 29.5" tall and 12.8" wide on a 18-inch rim — roughly a 29.5x13.00R18 in inch sizing.
What does 325/45R18 mean?
325 mm section width, sidewall 45% of the width (5.76"), radial construction, 18-inch rim.
What tire sizes are equivalent to 325/45R18?
On the same 18" rim, within 3% of the diameter: 225/65R18 (0.00%), 265/55R18 (-0.13%), 245/60R18 (+0.20%), 165/90R18 (+0.60%), 285/50R18 (-1.00%), 275/55R18 (+1.33%).
How many revolutions per mile does a 325/45R18 tire make?
About 683 revolutions per mile (circumference 92.7").
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.