165/90R18 tire size
165/90R18 is a metric size: 29.7" tall, 6.5" wide, on a 18" rim — about a 29.5x6.50R18. The sidewall is 5.8" and the tire turns 679 times per mile.
165/90R18 specs
| Overall diameter (height) | 29.69" · 754 mm |
|---|---|
| Section width | 6.50" · 165 mm |
| Sidewall height | 5.85" · 149 mm (90% of width) |
| Rim diameter | 18" |
| Circumference | 93.28" · 2.369 m |
| Revolutions per mile | 679 (422 per km) |
| Inch (flotation) equivalent | 29.5x6.50R18 |
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 | |
|---|---|---|---|---|---|
| 235/60R18 common | 29.10" | -1.99% | +70 mm | 58.8 mph | calculate → |
| 265/60R18 common | 30.52" | +2.78% | +100 mm | 61.7 mph | calculate → |
| 225/60R18 common | 28.63" | -3.58% | +60 mm | 57.9 mph | calculate → |
| 245/60R18 common | 29.57" | -0.40% | +80 mm | 59.8 mph | calculate → |
| 255/55R18 common | 29.04" | -2.19% | +90 mm | 58.7 mph | calculate → |
| 235/65R18 common | 30.03" | +1.13% | +70 mm | 60.7 mph | calculate → |
| 255/65R18 common | 31.05" | +4.57% | +90 mm | 62.7 mph | calculate → |
| 255/60R18 | 30.05" | +1.19% | +90 mm | 60.7 mph | calculate → |
| 245/55R18 | 28.61" | -3.65% | +80 mm | 57.8 mph | calculate → |
| 275/60R18 | 30.99" | +4.38% | +110 mm | 62.6 mph | calculate → |
| 295/45R18 | 28.45" | -4.18% | +130 mm | 57.5 mph | calculate → |
| 155/90R18 | 28.98" | -2.39% | -10 mm | 58.6 mph | calculate → |
| 285/50R18 | 29.22" | -1.59% | +120 mm | 59.0 mph | calculate → |
| 305/45R18 | 28.81" | -2.98% | +140 mm | 58.2 mph | calculate → |
| 155/85R18 | 28.37" | -4.44% | -10 mm | 57.3 mph | calculate → |
| 325/45R18 | 29.52" | -0.60% | +160 mm | 59.6 mph | calculate → |
| 275/55R18 | 29.91" | +0.73% | +110 mm | 60.4 mph | calculate → |
| 285/55R18 | 30.34" | +2.19% | +120 mm | 61.3 mph | calculate → |
| 175/90R18 | 30.40" | +2.39% | +10 mm | 61.4 mph | calculate → |
| 245/65R18 | 30.54" | +2.85% | +80 mm | 61.7 mph | calculate → |
| 235/70R18 | 30.95" | +4.24% | +70 mm | 62.5 mph | calculate → |
| 225/65R18 | 29.52" | -0.60% | +60 mm | 59.6 mph | calculate → |
| 265/55R18 | 29.48" | -0.73% | +100 mm | 59.6 mph | calculate → |
| 265/50R18 | 28.43" | -4.24% | +100 mm | 57.5 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 | |
|---|---|---|---|---|---|
| 245/65R17 common | 29.54" | -0.52% | +80 mm | 59.7 mph | calculate → |
| 245/55R19 common | 29.61" | -0.28% | +80 mm | 59.8 mph | calculate → |
| 265/50R19 common | 29.43" | -0.88% | +100 mm | 59.5 mph | calculate → |
| 235/70R17 | 29.95" | +0.88% | +70 mm | 60.5 mph | calculate → |
| 275/50R19 | 29.83" | +0.45% | +110 mm | 60.3 mph | calculate → |
| 265/60R17 | 29.52" | -0.58% | +100 mm | 59.6 mph | calculate → |
| 295/45R19 | 29.45" | -0.81% | +130 mm | 59.5 mph | calculate → |
| 175/90R17 | 29.40" | -0.98% | +10 mm | 59.4 mph | calculate → |
| 225/70R17 | 29.40" | -0.98% | +60 mm | 59.4 mph | calculate → |
Try another size against 165/90R18
Questions
What size is 165/90R18 in inches?
165/90R18 is about 29.7" tall and 6.5" wide on a 18-inch rim — roughly a 29.5x6.50R18 in inch sizing.
What does 165/90R18 mean?
165 mm section width, sidewall 90% of the width (5.85"), radial construction, 18-inch rim.
What tire sizes are equivalent to 165/90R18?
On the same 18" rim, within 3% of the diameter: 245/60R18 (-0.40%), 225/65R18 (-0.60%), 325/45R18 (-0.60%), 265/55R18 (-0.73%), 275/55R18 (+0.73%), 235/65R18 (+1.13%).
How many revolutions per mile does a 165/90R18 tire make?
About 679 revolutions per mile (circumference 93.3").
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.