145/80R12 Tire Size
145/80R12 diameter, sidewall, revolutions per mile, and plus-sizing options.
The 145/80R12 tire size breaks down as: 145 mm section width, 80% aspect ratio, and a 12-inch rim. Below are its real, calculated dimensions.
145/80R12 Calculated Dimensions
| Metric | Value |
|---|---|
| Overall diameter | 21.1 in (537 mm) |
| Sidewall height | 4.6 in (116 mm) |
| Circumference | 66.4 in (1686 mm) |
| Revolutions per mile | 954 |
Typical Fitment
145/80R12 is most often found on kei cars and classic small vehicles. Always confirm against the door-jamb placard or owner manual before fitting.
Plus-Sizing Alternatives
These sizes keep the overall diameter close to 145/80R12, so speedometer and gearing stay near stock:
| Size | Diameter | Diameter change |
|---|---|---|
| 155/75R12 | 21.15 in | +0.1% |
| 155/65R13 | 20.93 in | -1.0% |
| 165/55R14 | 21.15 in | +0.1% |
Speedometer Note
If you fit a 155/75R12 instead of 145/80R12, the diameter changes by +0.1%. A taller tire makes your speedometer read low — at a true 60 mph it would show roughly 60 mph. A shorter tire has the opposite effect, so the gauge reads high.
Use the tire calculator to compare 145/80R12 against any other size and see the exact diameter and speedometer difference.
Frequently Asked Questions
What does 145/80R12 mean?
145/80R12 means a 145 mm wide tire with a 80% sidewall aspect ratio mounted on a 12-inch rim. The aspect ratio is the sidewall height as a percentage of the width.
Can I plus-size from 145/80R12?
Yes, as long as the replacement keeps the overall diameter close to stock so the speedometer stays accurate. Common plus-size moves from 145/80R12 are 155/75R12, 155/65R13, 165/55R14.
Will 145/80R12 affect my speedometer?
Only if it differs in diameter from your original size. A taller tire reads low; a shorter tire reads high. Compare the two sizes with the calculator to find the percentage.