185/65R15 vs 195/60R15
Switching from 185/65R15 to 195/60R15 changes the overall diameter by -6.5 mm (-1.0%) — inside the commonly used ±3% guideline. Every figure below is calculated from the two size codes with the standard formulas.
| Measurement | 185/65R15 | 195/60R15 | Difference |
|---|---|---|---|
| Overall diameter | 621.5 mm | 615.0 mm | -6.5 mm (-1.0%) |
| Overall diameter | 24.47 in | 24.21 in | -0.26 in |
| Tire width | 185 mm (7.28 in) | 195 mm (7.68 in) | +10 mm |
| Sidewall height | 120.3 mm (4.73 in) | 117.0 mm (4.61 in) | -3.3 mm |
| Wheel (rim) diameter | 15.0 in | 15.0 in | 0.0 in |
| Circumference | 1952 mm | 1932 mm | -20 mm |
| Revolutions per mile | 2589 | 2617 | +27 |
| Revolutions per km | 512 | 518 | +5 |
Speedometer error
Calibrated for 185/65R15, the speedometer under-reads or over-reads once 195/60R15 is fitted. This is your real speed at each indicated speed:
| Speedometer shows | Actual speed on 195/60R15 | Error |
|---|---|---|
| 20 mph | 19.8 mph | -0.2 mph |
| 40 mph | 39.6 mph | -0.4 mph |
| 60 mph | 59.4 mph | -0.6 mph |
| 80 mph | 79.2 mph | -0.8 mph |
| 100 mph | 99.0 mph | -1.0 mph |
How these two sizes are worked out
185/65R15 breaks down as a 185 mm tread width with a sidewall of 65% of that width (120.3 mm) on a 15.0-inch wheel, giving an overall diameter of 621.5 mm (24.47 in). 195/60R15 works out to 615.0 mm (24.21 in) the same way. The standard formulas are the same ones used on the tire size calculator page: diameter = rim × 25.4 + 2 × sidewall, circumference = π × diameter, revolutions per mile = 63,360 ÷ diameter in inches.
Nominal sizes vary slightly between brands and models, and tread wear shrinks a tire over its life. These figures follow the size codes exactly; your vehicle manual or a professional tire shop is the authority for what fits your vehicle.
More comparisons
Frequently asked questions
Can I replace 185/65R15 tires with 195/60R15?
The diameter change is -1.0%, which is within the commonly used ±3% guideline. Diameter is only one part of fitment — wheel width range, load index, speed rating and physical clearance all have to check out too, so confirm with your vehicle manual or a professional tire shop before buying.
Will 195/60R15 make my speedometer read wrong?
Yes, by the diameter ratio. When the dial shows 60 mph you are really doing 59.4 mph on 195/60R15. The full table above covers 20 to 100 mph.
Which tire is taller, 185/65R15 or 195/60R15?
185/65R15 is taller — 621.5 mm against 615.0 mm overall diameter, a difference of 6.5 mm.