235/55R17 vs 245/55R17
Going from one to the other changes the overall height by +1.6 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 235/55R17 | 245/55R17 | Change |
|---|---|---|---|
| Overall height | 27.2" | 27.6" | +1.6 % |
| Sidewall | 5.09" | 5.31" | +4.3 % |
| Section width | 235 mm | 245 mm | +4.3 % |
| Circumference | 85.4" | 86.7" | +1.6 % |
| Revs per mile | 742 | 730 | -1.6 % |
| Axle height | 13.59" | 13.81" | +5.5 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 235/55R17. Fit 245/55R17 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.5 mph | +0.5 |
| 50 mph | 50.8 mph | +0.8 |
| 70 mph | 71.1 mph | +1.1 |
| 90 mph | 91.4 mph | +1.4 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,159 on the road, so it under-counts by 159. At a true 70 mph the first turns 866 times a minute, the second 852.
What drivers reported
235/55R17 carries 68 complaints. Nobody has filed one naming 245/55R17.