185/65R14 vs 175/65R14
Going from one to the other changes the overall height by -2.2 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 185/65R14 | 175/65R14 | Change |
|---|---|---|---|
| Overall height | 23.5" | 23.0" | -2.2 % |
| Sidewall | 4.73" | 4.48" | -5.4 % |
| Section width | 185 mm | 175 mm | -5.4 % |
| Circumference | 73.7" | 72.1" | -2.2 % |
| Revs per mile | 859 | 879 | +2.2 % |
| Axle height | 11.73" | 11.48" | -6.5 mm |
| Approved rim width | 5–6.5" | 5–6" | overlap 5–6" |
Both are approved on a rim 5" to 6" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 185/65R14. Fit 175/65R14 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.3 mph | -0.7 |
| 50 mph | 48.9 mph | -1.1 |
| 70 mph | 68.5 mph | -1.5 |
| 90 mph | 88.0 mph | -2.0 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,782 on the road, so it over-counts by 218. At a true 70 mph the first turns 1003 times a minute, the second 1025.