235/45R15 vs 225/45R15
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 | 235/45R15 | 225/45R15 | Change |
|---|---|---|---|
| Overall height | 23.3" | 23.0" | -1.5 % |
| Sidewall | 4.16" | 3.99" | -4.3 % |
| Section width | 235 mm | 225 mm | -4.3 % |
| Circumference | 73.3" | 72.2" | -1.5 % |
| Revs per mile | 865 | 878 | +1.5 % |
| Axle height | 11.66" | 11.49" | -4.5 mm |
| Approved rim width | 6.5–8.5" | 6–8.5" | overlap 6.5–8.5" |
Both are approved on a rim 6.5" 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 235/45R15. Fit 225/45R15 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 9,848 on the road, so it over-counts by 152. At a true 70 mph the first turns 1009 times a minute, the second 1024.
What drivers reported
Nobody has filed a complaint naming 235/45R15. 225/45R15 carries 2.