215/40R14 vs 225/35R14
Going from one to the other changes the overall height by -2.7 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 215/40R14 | 225/35R14 | Change |
|---|---|---|---|
| Overall height | 20.8" | 20.2" | -2.7 % |
| Sidewall | 3.39" | 3.10" | -8.4 % |
| Section width | 215 mm | 225 mm | +4.7 % |
| Circumference | 65.3" | 63.5" | -2.7 % |
| Revs per mile | 971 | 998 | +2.7 % |
| Axle height | 10.39" | 10.10" | -7.3 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 215/40R14. Fit 225/35R14 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.2 mph | -0.8 |
| 50 mph | 48.6 mph | -1.4 |
| 70 mph | 68.1 mph | -1.9 |
| 90 mph | 87.5 mph | -2.5 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,725 on the road, so it over-counts by 275. At a true 70 mph the first turns 1133 times a minute, the second 1165.