215/80R14 vs 225/75R14
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 | 215/80R14 | 225/75R14 | Change |
|---|---|---|---|
| Overall height | 27.5" | 27.3" | -0.9 % |
| Sidewall | 6.77" | 6.64" | -1.9 % |
| Section width | 215 mm | 225 mm | +4.7 % |
| Circumference | 86.5" | 85.7" | -0.9 % |
| Revs per mile | 732 | 739 | +0.9 % |
| Axle height | 13.77" | 13.64" | -3.3 mm |
| Approved rim width | 6–8" | 6–8.5" | overlap 6–8" |
Both are approved on a rim 6" to 8" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 215/80R14. Fit 225/75R14 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.7 mph | -0.3 |
| 50 mph | 49.5 mph | -0.5 |
| 70 mph | 69.3 mph | -0.7 |
| 90 mph | 89.2 mph | -0.8 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,907 on the road, so it over-counts by 93. At a true 70 mph the first turns 854 times a minute, the second 862.