Metric tire size
225/50R18 tire size
A 225/50R18 tire is 26.9 inches (682 mm) tall and 8.9 in wide, for a 18-inch wheel, with a 4.4 in sidewall. That is the nominal size worked out from the code. Makers publish 26.7–27.2 in for real 225/50R18 tires (7 makers).
Compare 225/50R18 with other sizes
Set up for: comparing 225/50R18 with a size you're considering · Different situation?
Your current size
e.g. 265/70R17, 2657017 or 33x12.50R20
Where do I find my size?
It's on the tire sidewall, e.g. P265/70R17 115T, and on the tire placard sticker on the driver's door jamb (also in the owner's manual). The placard shows the size the vehicle came with; the sidewall shows what is fitted now. If they differ, use the placard as your starting point. Digits are enough here: 2657017 or 33125020.
Size you're considering
Real 225/50R18 tires: published diameters
Figures from the makers' own data books. They differ from the 26.9 in calculated figure because each tread design and construction measures slightly differently.
| Maker (data book) | Published diameter | Revs per mile | Approved wheel width | Listings |
|---|---|---|---|---|
| BFGoodrich | 26.8 in | 774 | 6–8 in | 1 |
| Falken | 26.9–27.2 in | 774–782 | 6–8 in | 4 |
| Goodyear | 26.9 in | 777–778 | 6–8 in | 2 |
| Hankook | 26.7–26.9 in | 771–778 | 6–8 in | 4 |
| Nitto | 26.89 in | — | 6–8 in | 1 |
| Toyo | 26.9 in | 773 | 6–8 in | 1 |
| Uniroyal | 26.8 in | 774 | 6–8 in | 1 |
Equivalent sizes on other wheels
Sizes that appear in the maker data books with a diameter within 3% of 225/50R18. Same diameter is only one part of fitting a different size.
| Wheel | Real sizes within 3% (closest first) |
|---|---|
| 15-inch | 215/70R15 , 255/60R15 , 295/50R15 |
| 16-inch | 215/65R16 , 225/60R16 , 235/60R16 |
| 17-inch | 225/55R17 , 255/50R17 , 245/50R17 |
| 18-inch | 285/40R18 , 245/45R18 , 315/35R18 |
| 20-inch | 345/25R20 , 245/35R20 , 295/30R20 |
| 22-inch | 235/30R22 |
Popular comparisons with 225/50R18
FAQ
How tall is a 225/50R18 tire?
26.9 inches (682 mm) calculated from the size code. Makers publish 26.7–27.2 in for real tires in this size; the difference comes from tread design and construction.
How do you work out the 225/50R18 diameter?
Sidewall = 225 mm × 50% = 112.5 mm. Diameter = 18 in wheel + 2 × 112.5 mm ÷ 25.4 = 26.86 in.
Is 225/50R18 a 27-inch tire?
It is about 26.9 in tall nominally, so it is close to 27 inches. Real tires in a size vary slightly by model; check the maker's spec sheet for the exact tire.
What sizes are equivalent to 225/50R18?
Real sizes within 3% of its diameter include 215/65R16 (+0.5%), 225/55R17 (−0.4%) and 345/25R20 (−0.2%). Equal diameter alone doesn't make a size suitable: wheel width, offset, clearance and load rating all matter.
How many revolutions per mile does a 225/50R18 make?
About 751 calculated from its unloaded diameter. Makers publish 771–782 revs per mile, measured under load (a loaded tire rolls on a slightly smaller radius), which is why published figures are higher.
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