165/70R13 vs 185/65R13
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 | 165/70R13 | 185/65R13 | Change |
|---|---|---|---|
| Overall height | 22.1" | 22.5" | +1.7 % |
| Sidewall | 4.55" | 4.73" | +4.1 % |
| Section width | 165 mm | 185 mm | +12.1 % |
| Circumference | 69.4" | 70.6" | +1.7 % |
| Revs per mile | 913 | 898 | -1.7 % |
| Axle height | 11.05" | 11.23" | +4.8 mm |
| Approved rim width | 4.5–6" | 5–6.5" | 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 165/70R13. Fit 185/65R13 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.5 mph | +0.5 |
| 50 mph | 50.8 mph | +0.8 |
| 70 mph | 71.2 mph | +1.2 |
| 90 mph | 91.5 mph | +1.5 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,169 on the road, so it under-counts by 169. At a true 70 mph the first turns 1065 times a minute, the second 1047.
What drivers reported
165/70R13 carries 2 complaints. Nobody has filed one naming 185/65R13.