305/65R18 tire size
305/65R18 is a metric size: 33.6" tall, 12.0" wide, on a 18" rim — about a 33.5x12.00R18. The sidewall is 7.8" and the tire turns 600 times per mile.
305/65R18 specs
| Overall diameter (height) | 33.61" · 854 mm |
|---|---|
| Section width | 12.01" · 305 mm |
| Sidewall height | 7.81" · 198 mm (65% of width) |
| Rim diameter | 18" |
| Circumference | 105.59" · 2.682 m |
| Revolutions per mile | 600 (373 per km) |
| Inch (flotation) equivalent | 33.5x12.00R18 |
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 | |
|---|---|---|---|---|---|
| 275/65R18 common | 32.07" | -4.57% | -30 mm | 57.3 mph | compare → |
| 275/70R18 common | 33.16" | -1.35% | -30 mm | 59.2 mph | compare → |
| 265/70R18 common | 32.61" | -2.99% | -40 mm | 58.2 mph | compare → |
| 255/70R18 common | 32.06" | -4.63% | -50 mm | 57.2 mph | compare → |
| 35x12.50R18 common | 35.00" | +4.13% | +13 mm | 62.5 mph | compare → |
| 285/65R18 common | 32.59" | -3.05% | -20 mm | 58.2 mph | compare → |
| 295/70R18 common | 34.26" | +1.93% | -10 mm | 61.2 mph | compare → |
| 33x12.50R18 | 33.00" | -1.82% | +13 mm | 58.9 mph | compare → |
| 285/75R18 | 34.83" | +3.63% | -20 mm | 62.2 mph | compare → |
| 325/65R18 | 34.63" | +3.05% | +20 mm | 61.8 mph | compare → |
| 305/70R18 | 34.81" | +3.57% | 0 mm | 62.1 mph | compare → |
| 285/70R18 | 33.71" | +0.29% | -20 mm | 60.2 mph | compare → |
| 305/60R18 | 32.41" | -3.57% | 0 mm | 57.9 mph | compare → |
| 325/60R18 | 33.35" | -0.76% | +20 mm | 59.5 mph | compare → |
| 245/75R18 | 32.47" | -3.40% | -60 mm | 58.0 mph | calculate → |
| 295/65R18 | 33.10" | -1.52% | -10 mm | 59.1 mph | calculate → |
| 35x11.50R18 | 35.00" | +4.13% | -13 mm | 62.5 mph | calculate → |
| 34x12.50R18 | 34.00" | +1.16% | +13 mm | 60.7 mph | calculate → |
| 33x11.50R18 | 33.00" | -1.82% | -13 mm | 58.9 mph | calculate → |
| 33x13.50R18 | 33.00" | -1.82% | +38 mm | 58.9 mph | calculate → |
| 33x13.00R18 | 33.00" | -1.82% | +25 mm | 58.9 mph | calculate → |
| 235/80R18 | 32.80" | -2.40% | -70 mm | 58.6 mph | calculate → |
| 35x13.00R18 | 35.00" | +4.13% | +25 mm | 62.5 mph | calculate → |
| 35x14.50R18 | 35.00" | +4.13% | +63 mm | 62.5 mph | calculate → |
| 33x10.50R18 | 33.00" | -1.82% | -38 mm | 58.9 mph | calculate → |
| 35x13.50R18 | 35.00" | +4.13% | +38 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.
Try another size against 305/65R18
Questions
What size is 305/65R18 in inches?
305/65R18 is about 33.6" tall and 12.0" wide on a 18-inch rim — roughly a 33.5x12.00R18 in inch sizing.
What does 305/65R18 mean?
305 mm section width, sidewall 65% of the width (7.81"), radial construction, 18-inch rim.
What tire sizes are equivalent to 305/65R18?
On the same 18" rim, within 3% of the diameter: 285/70R18 (+0.29%), 325/60R18 (-0.76%), 34x12.50R18 (+1.16%), 275/70R18 (-1.35%), 295/65R18 (-1.52%), 33x10.50R18 (-1.82%).
How many revolutions per mile does a 305/65R18 tire make?
About 600 revolutions per mile (circumference 105.6").
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.