185/80R13 vs 205/75R13
Going from one to the other changes the overall height by +1.8 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 185/80R13 | 205/75R13 | Change |
|---|---|---|---|
| Overall height | 24.7" | 25.1" | +1.8 % |
| Sidewall | 5.83" | 6.05" | +3.9 % |
| Section width | 185 mm | 205 mm | +10.8 % |
| Circumference | 77.5" | 78.9" | +1.8 % |
| Revs per mile | 818 | 803 | -1.8 % |
| Axle height | 12.33" | 12.55" | +5.8 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 185/80R13. Fit 205/75R13 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.6 mph | +0.6 |
| 50 mph | 50.9 mph | +0.9 |
| 70 mph | 71.3 mph | +1.3 |
| 90 mph | 91.7 mph | +1.7 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,184 on the road, so it under-counts by 184. At a true 70 mph the first turns 954 times a minute, the second 937.
What drivers reported
185/80R13 carries 5 complaints. Nobody has filed one naming 205/75R13.