235/35R23 vs 245/35R23
Going from one to the other changes the overall height by +0.9 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 235/35R23 | 245/35R23 | Change |
|---|---|---|---|
| Overall height | 29.5" | 29.8" | +0.9 % |
| Sidewall | 3.24" | 3.38" | +4.3 % |
| Section width | 235 mm | 245 mm | +4.3 % |
| Circumference | 92.6" | 93.5" | +0.9 % |
| Revs per mile | 684 | 678 | -0.9 % |
| Axle height | 14.74" | 14.88" | +3.5 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 235/35R23. Fit 245/35R23 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.3 mph | +0.3 |
| 50 mph | 50.5 mph | +0.5 |
| 70 mph | 70.7 mph | +0.7 |
| 90 mph | 90.8 mph | +0.8 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,093 on the road, so it under-counts by 93. At a true 70 mph the first turns 798 times a minute, the second 791.