225/70R16 vs 205/80R16
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 | 225/70R16 | 205/80R16 | Change |
|---|---|---|---|
| Overall height | 28.4" | 28.9" | +1.8 % |
| Sidewall | 6.20" | 6.46" | +4.1 % |
| Section width | 225 mm | 205 mm | -8.9 % |
| Circumference | 89.2" | 90.8" | +1.8 % |
| Revs per mile | 710 | 698 | -1.8 % |
| Axle height | 14.20" | 14.46" | +6.5 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 225/70R16. Fit 205/80R16 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.5 mph | +0.5 |
| 50 mph | 50.9 mph | +0.9 |
| 70 mph | 71.3 mph | +1.3 |
| 90 mph | 91.6 mph | +1.6 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,180 on the road, so it under-counts by 180. At a true 70 mph the first turns 828 times a minute, the second 814.
What drivers reported
225/70R16 carries 58 complaints. Nobody has filed one naming 205/80R16.