185/65R15 — 24.47 in, and its twin on a 16-inch wheel
The supermini standard, and one half of the closest diameter match in the catalogue.
Metric notation · Passenger touring
- Overall diameter
- 24.47 in
- 622 mm
- Section width
- 7.28 in
- 185 mm
- Sidewall height
- 4.73 in
- 120 mm
- Aspect ratio
- 65%
- sidewall as a share of width
- Wheel diameter
- 15 in
- the hole in the middle
- Circumference
- 76.9 in
- 1952 mm
- Revolutions per mile
- 824.2
- geometric, not measured
- Revolutions per km
- 512.2
- geometric, not measured
- Typical load index
- 82–99
- 1047–1709 lb per tire
A passenger tire's load index tracks its air volume, and volume tracks section width and sidewall height. Sizes in this class sit in the band that carries a typical two-tonne car with its rated payload across four tires.
The load-index range shown is the band this CLASS of size is typically produced in — not a list of what is in stock for this exact size today. Load index and speed symbol are printed on the sidewall of the specific tire you are holding, and the required minimum is on the placard of the specific vehicle you are fitting. Read both.
Nearest real sizes in imperial notation, same wheel
- 30x9.50R1530.00 in tall+5.53 in
- 31x10.50R1531.00 in tall+6.53 in
- 32x11.50R1532.00 in tall+7.53 in
Compare any two sizes, including ones this site has no page for, in the comparison tool.
185/65R15 works out at 24.47 in tall, 7.28 in across the section, with a 4.73 in sidewall and 824.2 revolutions per mile. It is the size supermini-class cars settled on when 14-inch wheels became too small for their brakes: Polo, Fabia, Ibiza, Yaris and Jazz in various generations, plus a long list of small estates and MPVs in base trim.
The two-hundredths match
195/55R16 measures 24.44 in. This size measures 24.47 in. The gap between them is 0.10%, which is inside the tolerance to which real casings are built.
They are not remotely the same tire. One runs a 4.73 in sidewall on a 15-inch wheel and 7.28 in of section; the other runs 4.22 in on a 16 and 7.68 in of section. But a wheel-speed sensor sees an identical rolling diameter, so a car calibrated for one and fitted with the other would show no measurable error at all.
Sizes within a quarter of an inch, across four wheel diameters
| Alternative | Wheel | Diameter | Difference | Sidewall |
|---|---|---|---|---|
| 195/55R16 | 16 in | 24.44 in | 0.02 in | 4.22 in |
| 215/45R17 | 17 in | 24.62 in | 0.15 in | 3.81 in |
| 195/60R15 | 15 in | 24.21 in | 0.26 in | 4.61 in |
Four wheel diameters, four aspect ratios, four section widths, and a total spread of 0.41 in between the tallest and the shortest. That is the plus-sizing principle operating across an entire market segment rather than within a single model line, and the plus sizing reference sets out the arithmetic behind it.
Steps within the 15-inch ladder
Staying on the same wheel and the same aspect ratio, 195/65R15 is 0.51 in taller at 24.98 in and 205/65R15 is 1.02 in taller at 25.49 in. Each 10 mm of section width is worth exactly 0.51 in here, because the sidewall is 65% of a number that is growing in even steps.
The part of the sidewall with a date on it
Supermini tires wear out slowly, and a set bought for a car doing five thousand miles a year can reach the end of its useful life on age rather than tread. The four-digit DOT code stamped into the sidewall gives the week and year of manufacture, and it is the only place that information exists. Reading it is covered in the DOT date code reference.
Related
- 30x9.50R1530.00 in tall
- 31x10.50R1531.00 in tall
- 32x11.50R1532.00 in tall
Class: Passenger touring. Every figure above is computed from the size code, not stored — see how these numbers are calculated.