195/65R15 means a 195 mm section width, a 65% aspect ratio, radial construction and a 15-inch wheel. That works out to a 126.8 mm sidewall and an overall diameter of about 634.5 mm.
The aspect ratio is a proportion, not a measurement: the same 45 gives a different sidewall height on a different width, and that changes both ride and handling. A lower ratio holds a corner better and transmits more of the road surface.
The classic small-car size — older Avante, Pride, Corolla.
What each number means
| 195 | Section width 195 mm |
|---|---|
| 65 | Aspect ratio 126.8 mm (65% × 195 mm) |
| R | Construction Radial |
| 15 | Wheel diameter 381 mm |
| Overall diameter | 634.5 mm 25" |
Compatible alternatives
| Size | Overall diameter | Diameter difference |
|---|---|---|
| 185/65R15 | 621.5 mm | -2% |
| 205/65R15 | 647.5 mm | +2% |
| 195/60R15 | 615 mm | -3.1% |
Load index and speed rating
After the size itself, a tyre wall carries something like 91V. The number is the load index — the weight one tyre can carry, 91 meaning 615 kg — and the letter is the speed rating, V meaning 240 km/h.
Never drop below the load index the manufacturer specified, even if the size matches. The original specification is printed on the label inside the driver’s door.