215/80R14 vs 235/70R14
Going from one to the other changes the overall height by -2.1 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 215/80R14 | 235/70R14 | Change |
|---|---|---|---|
| Overall height | 27.5" | 27.0" | -2.1 % |
| Sidewall | 6.77" | 6.48" | -4.4 % |
| Section width | 215 mm | 235 mm | +9.3 % |
| Circumference | 86.5" | 84.7" | -2.1 % |
| Revs per mile | 732 | 748 | +2.1 % |
| Axle height | 13.77" | 13.48" | -7.5 mm |
| Approved rim width | 6–8" | 6.5–8.5" | overlap 6.5–8" |
Both are approved on a rim 6.5" 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 235/70R14 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.4 mph | -0.6 |
| 50 mph | 48.9 mph | -1.1 |
| 70 mph | 68.5 mph | -1.5 |
| 90 mph | 88.1 mph | -1.9 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,786 on the road, so it over-counts by 214. At a true 70 mph the first turns 854 times a minute, the second 873.