235/60R17 vs 215/70R17
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 | 235/60R17 | 215/70R17 | Change |
|---|---|---|---|
| Overall height | 28.1" | 28.9" | +2.7 % |
| Sidewall | 5.55" | 5.93" | +6.7 % |
| Section width | 235 mm | 215 mm | -8.5 % |
| Circumference | 88.3" | 90.6" | +2.7 % |
| Revs per mile | 718 | 699 | -2.7 % |
| Axle height | 14.05" | 14.43" | +9.5 mm |
| Approved rim width | 6.5–8.5" | 6–8" | 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 235/60R17. Fit 215/70R17 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.8 mph | +0.8 |
| 50 mph | 51.3 mph | +1.3 |
| 70 mph | 71.9 mph | +1.9 |
| 90 mph | 92.4 mph | +2.4 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,266 on the road, so it under-counts by 266. At a true 70 mph the first turns 837 times a minute, the second 816.
What drivers reported
235/60R17 carries 18 complaints. Nobody has filed one naming 215/70R17.