225/65R17 Tire Size in Inches
A 225/65R17 tire has an overall diameter of 28.52 in (724.3 mm), a 5.76 in sidewall, a 89.58 in circumference, and turns about 707 revolutions per mile. These are nominal dimensions from the size code — real tires vary ~±3% by brand.
Nominal dimensions from the size code — real tires vary ~±3% by brand, model and rim width. Keep a replacement within 3% of your OEM diameter so the speedometer stays accurate.
How to read a tire size
A code like 225/45R17 packs three numbers: 225 is the section width in millimetres, 45 is the aspect ratio (the sidewall height is 45% of the width), and 17 is the wheel/rim diameter in inches. The R just means radial construction.
From those three numbers the overall diameter, sidewall height, circumference and revolutions per mile are pure geometry — there's no lookup table or guesswork. The one exact constant is 1 inch = 25.4 mm.
How it's calculated
Sidewall height (mm) = width × aspect ÷ 100
Overall diameter (mm) = 2 × sidewall + rim × 25.4
Circumference = diameter × π · Revs per mile = 63,360 ÷ circumference (in)
Example — 225/45R17: sidewall 101.25 mm (3.99 in), diameter 634.3 mm (24.97 in), circumference 78.45 in, ≈808 revs/mile.
Common tire sizes in inches
| Size | Diameter | Sidewall | Revs/mi |
|---|---|---|---|
| 225/45R17 | 24.97 in | 3.99 in | 808 |
| 205/55R16 | 24.88 in | 4.44 in | 811 |
| 215/55R17 | 26.31 in | 4.66 in | 767 |
| 225/65R17 | 28.52 in | 5.76 in | 707 |
| 235/45R18 | 26.33 in | 4.16 in | 766 |
| 245/45R18 | 26.68 in | 4.34 in | 756 |
| 265/70R17 | 31.61 in | 7.30 in | 638 |
| 275/55R20 | 31.91 in | 5.95 in | 632 |
| 285/70R17 | 32.71 in | 7.85 in | 617 |
| 305/35R20 | 28.41 in | 4.20 in | 710 |
| 195/65R15 | 24.98 in | 4.99 in | 807 |
| 215/45R17 | 24.62 in | 3.81 in | 819 |
FAQ
No — they are the nominal dimensions defined by the size code. A real tire's measured diameter and width vary by manufacturer, model, tread and the rim width it's mounted on. Standards bodies (ETRTO/TRA) allow roughly ±3%, and section width can vary even more.
As a rule of thumb, keep the new overall diameter within 3% of the original so your speedometer, odometer and ABS stay accurate. Use the calculator to compare both sizes' diameters.
A larger overall diameter travels further per revolution, so the speedometer reads lower than your true speed (you're actually going faster than it shows). A smaller diameter does the opposite.
It marks radial construction, which is standard on modern passenger tires. The geometry here is the same regardless of construction type.