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305/65R18 tire size in inches
305/65R18 is 33.61" tall and 12.01" wide, and fits a 18" rim. In flotation (inch) sizing that is roughly 33.6x12.0R18.
305/65R18 dimensions
| Measurement | Inches | Metric |
|---|---|---|
| Overall diameter (height) | 33.61" | 854 mm |
| Section width | 12.01" | 305 mm |
| Sidewall height | 7.81" | 198.2 mm |
| Rim diameter | 18" | 457.2 mm |
| Circumference | 105.6" | 2682 mm |
| Revolutions per mile | 600 | |
| Aspect ratio | 65% (sidewall is 65% of the width) | |
Drawn to scale
Among the 122 sizes for 18" wheels on this site, 305/65R18 is #89 by height (shortest: 245/35R18, tallest: 340/80R18).
What people compare 305/65R18 with
Real comparisons drivers search for, worked out against 305/65R18:
| Compared size | Height | Width | Sidewall | Speedo at true 60 |
|---|---|---|---|---|
| 295/70R18 | +0.65" (+1.93%) | -0.40" | +0.32" | 58.9 mph |
| 275/70R18 | -0.45" (-1.34%) | -1.18" | -0.23" | 60.8 mph |
305/65R18 against the most popular 18" sizes
| Popular size | Height | Width | Sidewall | Speedo at true 60 |
|---|---|---|---|---|
| 275/65R18 | -1.54" (-4.58%) | -1.18" | -0.77" | 62.9 mph |
| 285/65R18 | -1.02" (-3.03%) | -0.79" | -0.52" | 61.9 mph |
| 305/70R18 | +1.20" (+3.57%) | 0.00" | +0.60" | 57.9 mph |
| 285/70R18 | +0.10" (+0.3%) | -0.79" | +0.04" | 59.8 mph |
| 285/75R18 | +1.22" (+3.63%) | -0.79" | +0.61" | 57.9 mph |
How the 305/65R18 numbers are worked out
The size code reads as 305 mm section width, 65% aspect ratio, R for radial construction and 18-inch wheel.
- Sidewall = 305 × 65% = 198.2 mm = 7.81"
- Diameter = 18" + 2 × 7.81" = 33.61"
- Circumference = π × 33.61" = 105.6"
- Revs per mile = 63,360" ÷ 105.6" = 600
Sizes that can replace 305/65R18 on a 18" wheel
Within 3% of 33.61". Last column: speedometer reading at a true 60 mph.
| Size | Diameter | Width | Difference | Speedo at true 60 mph |
|---|---|---|---|---|
| 265/75R18 | 33.65" | 10.43" | +0.12% | 59.9 mph |
| 285/70R18 | 33.71" | 11.22" | +0.3% | 59.8 mph |
| 280/70R18 | 33.43" | 11.02" | -0.54% | 60.3 mph |
| 325/60R18 | 33.35" | 12.80" | -0.77% | 60.5 mph |
| 270/75R18 | 33.94" | 10.63" | +0.98% | 59.4 mph |
| 290/70R18 | 33.98" | 11.42" | +1.1% | 59.3 mph |
| 275/70R18 | 33.16" | 10.83" | -1.34% | 60.8 mph |
| 255/80R18 | 34.06" | 10.04" | +1.34% | 59.2 mph |
| 295/65R18 | 33.10" | 11.61" | -1.52% | 60.9 mph |
| 315/65R18 | 34.12" | 12.40" | +1.52% | 59.1 mph |
| 255/75R18 | 33.06" | 10.04" | -1.64% | 61 mph |
| 275/75R18 | 34.24" | 10.83" | +1.87% | 58.9 mph |
One size wider or narrower
- Narrower: 295/65R18 — 11.61" wide, 33.10" tall
- Wider: 315/65R18 — 12.40" wide, 34.12" tall
Same height on a different wheel size
- 315/75R15 15" (-0.03%)
- 325/75R15 15" (+1.73%)
- 305/75R15 15" (-1.79%)
- 265/85R16 16" (+0.39%)
- 295/75R16 16" (-0.57%)
- 315/70R16 16" (-0.74%)
- 275/80R16 16" (-0.86%)
- 325/70R16 16" (+0.89%)
- 285/80R16 16" (+1.01%)
- 305/75R16 16" (+1.19%)
Questions about 305/65R18
How tall is a 305/65R18 tire in inches?
A 305/65R18 tire is 33.61 inches (854 mm) tall: the 18-inch rim plus two sidewalls of 7.81 inches each.
Is 305/65R18 a 34 inch tire?
Yes. At 33.61 inches tall it is commonly called a 34-inch tire.
How many revolutions per mile does a 305/65R18 make?
About 600 revolutions per mile, based on a calculated circumference of 105.6 inches.
What size can replace 305/65R18?
265/75R18 is the closest match on a 18" rim (+0.12% height). Check load index, speed rating and clearance first.
Compare 305/65R18 against any other size with the tire size calculator.