205/40R15 vs 225/35R15
Going from one to the other changes the overall height by -1.2 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 205/40R15 | 225/35R15 | Change |
|---|---|---|---|
| Overall height | 21.5" | 21.2" | -1.2 % |
| Sidewall | 3.23" | 3.10" | -4.0 % |
| Section width | 205 mm | 225 mm | +9.8 % |
| Circumference | 67.4" | 66.6" | -1.2 % |
| Revs per mile | 940 | 951 | +1.2 % |
| Axle height | 10.73" | 10.60" | -3.3 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 205/40R15. Fit 225/35R15 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.6 mph | -0.4 |
| 50 mph | 49.4 mph | -0.6 |
| 70 mph | 69.2 mph | -0.8 |
| 90 mph | 88.9 mph | -1.1 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,881 on the road, so it over-counts by 119. At a true 70 mph the first turns 1097 times a minute, the second 1110.