235/60R17 vs 245/55R17
Going from one to the other changes the overall height by -1.8 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 235/60R17 | 245/55R17 | Change |
|---|---|---|---|
| Overall height | 28.1" | 27.6" | -1.8 % |
| Sidewall | 5.55" | 5.31" | -4.4 % |
| Section width | 235 mm | 245 mm | +4.3 % |
| Circumference | 88.3" | 86.7" | -1.8 % |
| Revs per mile | 718 | 730 | +1.8 % |
| Axle height | 14.05" | 13.81" | -6.3 mm |
| Approved rim width | 6.5–8.5" | 7–9" | 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 235/60R17. Fit 245/55R17 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.5 mph | -0.5 |
| 50 mph | 49.1 mph | -0.9 |
| 70 mph | 68.8 mph | -1.2 |
| 90 mph | 88.4 mph | -1.6 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,825 on the road, so it over-counts by 175. At a true 70 mph the first turns 837 times a minute, the second 852.
What drivers reported
235/60R17 carries 18 complaints. Nobody has filed one naming 245/55R17.