185/75R14 vs 205/65R14
Going from one to the other changes the overall height by -1.7 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 185/75R14 | 205/65R14 | Change |
|---|---|---|---|
| Overall height | 24.9" | 24.5" | -1.7 % |
| Sidewall | 5.46" | 5.25" | -4.0 % |
| Section width | 185 mm | 205 mm | +10.8 % |
| Circumference | 78.3" | 76.9" | -1.7 % |
| Revs per mile | 809 | 823 | +1.7 % |
| Axle height | 12.46" | 12.25" | -5.5 mm |
| Approved rim width | 5–6.5" | 5.5–7.5" | 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 185/75R14. Fit 205/65R14 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.5 mph | -0.5 |
| 50 mph | 49.1 mph | -0.9 |
| 70 mph | 68.8 mph | -1.2 |
| 90 mph | 88.4 mph | -1.6 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,826 on the road, so it over-counts by 174. At a true 70 mph the first turns 944 times a minute, the second 961.
What drivers reported
185/75R14 carries 21 complaints. Nobody has filed one naming 205/65R14.