185/60R15 vs 195/60R15
Going from one to the other changes the overall height by +2.0 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 185/60R15 | 195/60R15 | Change |
|---|---|---|---|
| Overall height | 23.7" | 24.2" | +2.0 % |
| Sidewall | 4.37" | 4.61" | +5.4 % |
| Section width | 185 mm | 195 mm | +5.4 % |
| Circumference | 74.6" | 76.1" | +2.0 % |
| Revs per mile | 850 | 833 | -2.0 % |
| Axle height | 11.87" | 12.11" | +6.0 mm |
| Approved rim width | 5–6.5" | 5.5–7" | overlap 5.5–6.5" |
Both are approved on a rim 5.5" to 6.5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 185/60R15. Fit 195/60R15 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.6 mph | +0.6 |
| 50 mph | 51.0 mph | +1.0 |
| 70 mph | 71.4 mph | +1.4 |
| 90 mph | 91.8 mph | +1.8 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,199 on the road, so it under-counts by 199. At a true 70 mph the first turns 991 times a minute, the second 972.