215/85R14 vs 235/80R14
Going from one to the other changes the overall height by +1.5 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 215/85R14 | 235/80R14 | Change |
|---|---|---|---|
| Overall height | 28.4" | 28.8" | +1.5 % |
| Sidewall | 7.19" | 7.40" | +2.9 % |
| Section width | 215 mm | 235 mm | +9.3 % |
| Circumference | 89.2" | 90.5" | +1.5 % |
| Revs per mile | 710 | 700 | -1.5 % |
| Axle height | 14.19" | 14.40" | +5.3 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 215/85R14. Fit 235/80R14 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.4 mph | +0.4 |
| 50 mph | 50.7 mph | +0.7 |
| 70 mph | 71.0 mph | +1.0 |
| 90 mph | 91.3 mph | +1.3 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,146 on the road, so it under-counts by 146. At a true 70 mph the first turns 829 times a minute, the second 817.