205/85R15 vs 225/75R15
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 | 205/85R15 | 225/75R15 | Change |
|---|---|---|---|
| Overall height | 28.7" | 28.3" | -1.5 % |
| Sidewall | 6.86" | 6.64" | -3.2 % |
| Section width | 205 mm | 225 mm | +9.8 % |
| Circumference | 90.2" | 88.9" | -1.5 % |
| Revs per mile | 702 | 713 | +1.5 % |
| Axle height | 14.36" | 14.14" | -5.5 mm |
| Approved rim width | 5.5–7.5" | 6–8.5" | 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 205/85R15. Fit 225/75R15 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 9,849 on the road, so it over-counts by 151. At a true 70 mph the first turns 819 times a minute, the second 832.
What drivers reported
Nobody has filed a complaint naming 205/85R15. 225/75R15 carries 258.