175/70R14 tyre size
600.6 mm diameter
23.65 in · 122.5 mm sidewall · 1.89 m rolling circumference · 530 rev/km
Reading 175/70R14
| 175 | Tread width in millimetres |
| 70 | Aspect ratio — sidewall height as a percentage of the width, so 175 × 70% = 122.5 mm |
| R | Radial construction, which is almost every road tyre made since the 1970s |
| 14 | Rim diameter in inches — 355.6 mm |
The aspect ratio is the part that catches people: it is a percentage of the width, not a fixed height. Widen the tread and keep the same aspect number and the tyre also gets taller. That is why 175/70R14 and a size with a smaller aspect number on a larger rim can be the same overall diameter.
The numbers
| Tread width | 175 mm · 6.89 in |
| Sidewall height | 122.5 mm · 4.82 in |
| Rim diameter | 14 in · 355.6 mm |
| Overall diameter | 600.6 mm · 23.65 in |
| Rolling circumference | 1886.8 mm · 1.89 m |
| Revolutions per kilometre | 530 |
| Revolutions per mile | 853 |
Sizes that fit in place of 175/70R14
A replacement is judged on rolling diameter, because that is what the speedometer, the ABS and the gearing all depend on. Anything within about 1% is treated as interchangeable; beyond 3% the speedometer error stops being ignorable.
| Size | Diameter | Difference | Speedometer at an indicated 100 |
|---|---|---|---|
| 195/60R15 | 615.0 mm | +2.40% | 102.4 km/h actual |
| 185/55R15 | 584.5 mm | -2.68% | 97.3 km/h actual |
| 175/65R14 | 583.1 mm | -2.91% | 97.1 km/h actual |
Diameter is only half the question — the replacement also has to suit the rim width and the vehicle's load and speed ratings. Check the placard in the door frame before buying.
Other 14-inch sizes
| Size | Sidewall | Diameter |
|---|---|---|
| 165/65R14 | 107.3 mm | 570.1 mm |
| 175/65R14 | 113.8 mm | 583.1 mm |
| 185/60R14 | 111.0 mm | 577.6 mm |
Frequently asked questions
What does 175/70R14 mean?
175 is the tread width in millimetres, 70 is the sidewall height as a percentage of that width — so 175 × 70% = 122.5 mm of sidewall — and R14 is a radial tyre on a 14-inch rim. Overall diameter is 14 × 25.4 + 2 × 122.5 = 600.6 mm.
What is the overall diameter of a 175/70R14?
600.6 mm (23.65 inches), with a rolling circumference of 1.89 m — about 530 revolutions per kilometre.
Is 175/70R14 an unusual size?
Nothing else in this list is within 1% of its diameter, so replacements need checking against the vehicle's placard rather than picked by eye.
How much does changing tyre size affect the speedometer?
A speedometer counts wheel revolutions, so it reads in proportion to the rolling diameter it was calibrated for. Fitting a tyre 1% larger makes the speedometer read 1% low — at an indicated 100 km/h you are doing 101. Most jurisdictions expect a speedometer to never under-read, which is why replacements are kept within about 3% and why the factory tyre usually reads a little high to begin with.