115/70R15 Tire Size
115/70R15 diameter, sidewall, revolutions per mile, and plus-sizing options.
The 115/70R15 tire size breaks down as: 115 mm section width, 70% aspect ratio, and a 15-inch rim. Below are its real, calculated dimensions.
115/70R15 Calculated Dimensions
| Metric | Value |
|---|---|
| Overall diameter | 21.3 in (542 mm) |
| Sidewall height | 3.2 in (81 mm) |
| Circumference | 67.0 in (1703 mm) |
| Revolutions per mile | 945 |
Typical Fitment
115/70R15 is most often found on compact cars and space-saver spares. Always confirm against the door-jamb placard or owner manual before fitting.
Plus-Sizing Alternatives
These sizes keep the overall diameter close to 115/70R15, so speedometer and gearing stay near stock:
| Size | Diameter | Diameter change |
|---|---|---|
| 125/65R15 | 21.40 in | +0.3% |
| 125/55R16 | 21.41 in | +0.4% |
| 135/40R17 | 21.25 in | -0.4% |
Speedometer Note
If you fit a 125/65R15 instead of 115/70R15, the diameter changes by +0.3%. 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 115/70R15 against any other size and see the exact diameter and speedometer difference.
Frequently Asked Questions
What does 115/70R15 mean?
115/70R15 means a 115 mm wide tire with a 70% sidewall aspect ratio mounted on a 15-inch rim. The aspect ratio is the sidewall height as a percentage of the width.
Can I plus-size from 115/70R15?
Yes, as long as the replacement keeps the overall diameter close to stock so the speedometer stays accurate. Common plus-size moves from 115/70R15 are 125/65R15, 125/55R16, 135/40R17.
Will 115/70R15 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.