Tire Sidewall Height Calculator
Calculate tire sidewall height from width and aspect ratio. Get the result in millimeters and inches for any metric tire size.
Calculate sidewall height from size markings.
Tire Sidewall Height Calculator: Tire Size Inputs
Compare two tire sizes here. Use the formulas and reference tables below for this tool's specific calculation.
How Tire Sidewall Height Calculator Works?
The Tire Sidewall Height Calculator works by multiplying the section width by the aspect ratio expressed as a decimal. The tool needs 2 inputs and 2 steps.
Enter width and aspect ratio
Type the first 2 numbers of the size code, for example 245 and 40 from 245/40 R18.
Multiply
The calculator multiplies 245 by 0.40 and returns a sidewall height of 98 mm (3.86 in).
Tire Sidewall Height Calculator Formula
The Tire Sidewall Height Calculator formula is SH = W × (AR ÷ 100).
SH = W × AR ÷ 100SH_in = SH ÷ 25.4- SH
- Sidewall height from bead seat to tread surface (mm)
- W
- Section width (mm)
- AR
- Aspect ratio (%)
Worked example
A 265/70 R17 tire has a sidewall height of 265 × 0.70 = 185.5 mm (7.30 in). A 255/35 R19 tire has a sidewall height of 255 × 0.35 = 89.25 mm (3.51 in).
Tire Sidewall Height Calculator Conversion Table
The Tire Sidewall Height Calculator conversion table gives sidewall height for 5 widths and 5 aspect ratios in millimeters and inches.
| Width | 35 series | 45 series | 55 series | 65 series | 75 series |
|---|---|---|---|---|---|
| 205 mm | 71.8 mm / 2.82 in | 92.2 mm / 3.63 in | 112.8 mm / 4.44 in | 133.2 mm / 5.25 in | 153.8 mm / 6.05 in |
| 225 mm | 78.8 mm / 3.10 in | 101.2 mm / 3.99 in | 123.8 mm / 4.87 in | 146.2 mm / 5.76 in | 168.8 mm / 6.64 in |
| 245 mm | 85.8 mm / 3.38 in | 110.2 mm / 4.34 in | 134.8 mm / 5.31 in | 159.2 mm / 6.27 in | 183.8 mm / 7.23 in |
| 265 mm | 92.8 mm / 3.65 in | 119.2 mm / 4.69 in | 145.8 mm / 5.74 in | 172.2 mm / 6.78 in | 198.8 mm / 7.82 in |
| 285 mm | 99.8 mm / 3.93 in | 128.2 mm / 5.05 in | 156.8 mm / 6.17 in | 185.2 mm / 7.29 in | 213.8 mm / 8.42 in |
What is Tire Sidewall Height Calculator?
A Tire Sidewall Height Calculator is a tool that converts the width and aspect ratio numbers of a tire size into the height of the sidewall. Sidewall height is the distance from the wheel's bead seat to the outer tread surface.
Sidewall height decides ride comfort, steering response and pothole protection for the wheel. A tall sidewall flexes more and cushions impacts. A short sidewall flexes less and gives sharper steering.
The aspect ratio is a percentage of width, so two tires with the same aspect ratio but different widths have different sidewall heights. A 205/55 tire has a 112.75 mm sidewall, and a 245/55 tire has a 134.75 mm sidewall.
What are the uses of Tire Sidewall Height Calculator?
There are 4 main uses of the Tire Sidewall Height Calculator, including rim protection checks and comfort comparisons.
Rim protection checks
Confirm enough sidewall exists to protect a large wheel from potholes.
Comfort comparisons
Compare sidewall height before switching to a lower-profile tire.
Diameter building
Supply the sidewall value to the overall diameter formula.
Visual styling
Preview how much rubber shows between rim and fender.
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