235/50R23 vs 245/50R23
Going from one to the other changes the overall height by +1.2 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 235/50R23 | 245/50R23 | Change |
|---|---|---|---|
| Overall height | 32.3" | 32.6" | +1.2 % |
| Sidewall | 4.63" | 4.82" | +4.3 % |
| Section width | 235 mm | 245 mm | +4.3 % |
| Circumference | 101.3" | 102.6" | +1.2 % |
| Revs per mile | 625 | 618 | -1.2 % |
| Axle height | 16.13" | 16.32" | +5.0 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 235/50R23. Fit 245/50R23 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.4 mph | +0.4 |
| 50 mph | 50.6 mph | +0.6 |
| 70 mph | 70.9 mph | +0.9 |
| 90 mph | 91.1 mph | +1.1 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,122 on the road, so it under-counts by 122. At a true 70 mph the first turns 730 times a minute, the second 721.