215/60R15 vs 235/55R15
Going from one to the other changes the overall height by +0.1 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 215/60R15 | 235/55R15 | Change |
|---|---|---|---|
| Overall height | 25.2" | 25.2" | +0.1 % |
| Sidewall | 5.08" | 5.09" | +0.2 % |
| Section width | 215 mm | 235 mm | +9.3 % |
| Circumference | 79.0" | 79.1" | +0.1 % |
| Revs per mile | 802 | 801 | -0.1 % |
| Axle height | 12.58" | 12.59" | +0.3 mm |
| Approved rim width | 6–8" | 6.5–8.5" | overlap 6.5–8" |
Both are approved on a rim 6.5" to 8" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 215/60R15. Fit 235/55R15 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.0 mph | +0.0 |
| 50 mph | 50.0 mph | +0.0 |
| 70 mph | 70.1 mph | +0.1 |
| 90 mph | 90.1 mph | +0.1 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,008 on the road, so it under-counts by 8. At a true 70 mph the first turns 935 times a minute, the second 935.
What drivers reported
215/60R15 carries 30 complaints. Nobody has filed one naming 235/55R15.