245/35R16 vs 225/35R16
Going from one to the other changes the overall height by -2.4 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 245/35R16 | 225/35R16 | Change |
|---|---|---|---|
| Overall height | 22.8" | 22.2" | -2.4 % |
| Sidewall | 3.38" | 3.10" | -8.2 % |
| Section width | 245 mm | 225 mm | -8.2 % |
| Circumference | 71.5" | 69.7" | -2.4 % |
| Revs per mile | 886 | 908 | +2.4 % |
| Axle height | 11.38" | 11.10" | -7.0 mm |
| Approved rim width | 7–9" | 6–8.5" | overlap 7–8.5" |
Both are approved on a rim 7" to 8.5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 245/35R16. Fit 225/35R16 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.3 mph | -0.7 |
| 50 mph | 48.8 mph | -1.2 |
| 70 mph | 68.3 mph | -1.7 |
| 90 mph | 87.8 mph | -2.2 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,758 on the road, so it over-counts by 242. At a true 70 mph the first turns 1034 times a minute, the second 1060.