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315/70R18 tire size in inches
315/70R18 is 35.36" tall and 12.40" wide, and fits a 18" rim. In flotation (inch) sizing that is roughly 35.4x12.4R18.
315/70R18 dimensions
| Measurement | Inches | Metric |
|---|---|---|
| Overall diameter (height) | 35.36" | 898 mm |
| Section width | 12.40" | 315 mm |
| Sidewall height | 8.68" | 220.5 mm |
| Rim diameter | 18" | 457.2 mm |
| Circumference | 111.1" | 2822 mm |
| Revolutions per mile | 570 | |
| Aspect ratio | 70% (sidewall is 70% of the width) | |
Drawn to scale
Among the 122 sizes for 18" wheels on this site, 315/70R18 is #106 by height (shortest: 245/35R18, tallest: 340/80R18).
315/70R18 against the most popular 18" sizes
| Popular size | Height | Width | Sidewall | Speedo at true 60 |
|---|---|---|---|---|
| 275/70R18 | -2.20" (-6.22%) | -1.57" | -1.10" | 64 mph |
| 275/65R18 | -3.29" (-9.3%) | -1.57" | -1.64" | 66.2 mph |
| 295/70R18 | -1.10" (-3.11%) | -0.79" | -0.55" | 61.9 mph |
| 285/65R18 | -2.77" (-7.83%) | -1.18" | -1.39" | 65.1 mph |
| 305/70R18 | -0.55" (-1.56%) | -0.39" | -0.27" | 60.9 mph |
How the 315/70R18 numbers are worked out
The size code reads as 315 mm section width, 70% aspect ratio, R for radial construction and 18-inch wheel.
- Sidewall = 315 × 70% = 220.5 mm = 8.68"
- Diameter = 18" + 2 × 8.68" = 35.36"
- Circumference = π × 35.36" = 111.1"
- Revs per mile = 63,360" ÷ 111.1" = 570
Sizes that can replace 315/70R18 on a 18" wheel
Within 3% of 35.36". Last column: speedometer reading at a true 60 mph.
| Size | Diameter | Width | Difference | Speedo at true 60 mph |
|---|---|---|---|---|
| 275/80R18 | 35.32" | 10.83" | -0.11% | 60.1 mph |
| 295/75R18 | 35.42" | 11.61" | +0.17% | 59.9 mph |
| 335/65R18 | 35.15" | 13.19" | -0.59% | 60.4 mph |
| 255/85R18 | 35.07" | 10.04" | -0.82% | 60.5 mph |
| 375/60R18 | 35.72" | 14.76" | +1.02% | 59.4 mph |
| 265/85R18 | 35.74" | 10.43" | +1.07% | 59.4 mph |
| 285/75R18 | 34.83" | 11.22" | -1.5% | 60.9 mph |
| 305/70R18 | 34.81" | 12.01" | -1.56% | 60.9 mph |
| 325/70R18 | 35.91" | 12.80" | +1.56% | 59.1 mph |
| 285/80R18 | 35.95" | 11.22" | +1.67% | 59 mph |
| 305/75R18 | 36.01" | 12.01" | +1.84% | 58.9 mph |
| 265/80R18 | 34.69" | 10.43" | -1.89% | 61.2 mph |
One size wider or narrower
- Narrower: 305/70R18 — 12.01" wide, 34.81" tall
- Wider: 325/70R18 — 12.80" wide, 35.91" tall
Same height on a different wheel size
- 305/80R16 16" (-0.42%)
- 325/75R16 16" (-0.48%)
- 375/65R16 16" (-0.48%)
- 285/85R16 16" (-0.82%)
- 295/85R16 16" (+1.07%)
- 335/75R16 16" (+1.19%)
- 315/80R16 16" (+1.36%)
- 275/85R17 17" (+0.14%)
- 335/70R17 17" (+0.28%)
- 295/80R17 17" (+0.62%)
Questions about 315/70R18
How tall is a 315/70R18 tire in inches?
A 315/70R18 tire is 35.36 inches (898 mm) tall: the 18-inch rim plus two sidewalls of 8.68 inches each.
Is 315/70R18 a 35 inch tire?
Yes. At 35.36 inches tall it is commonly called a 35-inch tire.
How many revolutions per mile does a 315/70R18 make?
About 570 revolutions per mile, based on a calculated circumference of 111.1 inches.
What size can replace 315/70R18?
275/80R18 is the closest match on a 18" rim (-0.11% height). Check load index, speed rating and clearance first.
Compare 315/70R18 against any other size with the tire size calculator.