225/80R16 vs 205/85R16
Going from one to the other changes the overall height by -1.5 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 225/80R16 | 205/85R16 | Change |
|---|---|---|---|
| Overall height | 30.2" | 29.7" | -1.5 % |
| Sidewall | 7.09" | 6.86" | -3.2 % |
| Section width | 225 mm | 205 mm | -8.9 % |
| Circumference | 94.8" | 93.4" | -1.5 % |
| Revs per mile | 668 | 679 | +1.5 % |
| Axle height | 15.09" | 14.86" | -5.8 mm |
| Approved rim width | 6–8.5" | 5.5–7.5" | overlap 6–7.5" |
Both are approved on a rim 6" to 7.5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 225/80R16. Fit 205/85R16 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.5 mph | -0.5 |
| 50 mph | 49.2 mph | -0.8 |
| 70 mph | 68.9 mph | -1.1 |
| 90 mph | 88.6 mph | -1.4 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,850 on the road, so it over-counts by 150. At a true 70 mph the first turns 780 times a minute, the second 792.
What drivers reported
225/80R16 carries 3 complaints. Nobody has filed one naming 205/85R16.