195/65R18 vs 215/55R18
Going from one to the other changes the overall height by -2.4 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 195/65R18 | 215/55R18 | Change |
|---|---|---|---|
| Overall height | 28.0" | 27.3" | -2.4 % |
| Sidewall | 4.99" | 4.66" | -6.7 % |
| Section width | 195 mm | 215 mm | +10.3 % |
| Circumference | 87.9" | 85.8" | -2.4 % |
| Revs per mile | 721 | 738 | +2.4 % |
| Axle height | 13.99" | 13.66" | -8.5 mm |
| Approved rim width | 5.5–7" | 6–8" | overlap 6–7" |
Both are approved on a rim 6" to 7" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 195/65R18. Fit 215/55R18 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.3 mph | -0.7 |
| 50 mph | 48.8 mph | -1.2 |
| 70 mph | 68.3 mph | -1.7 |
| 90 mph | 87.8 mph | -2.2 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,761 on the road, so it over-counts by 239. At a true 70 mph the first turns 841 times a minute, the second 862.
What drivers reported
Nobody has filed a complaint naming 195/65R18. 215/55R18 carries 10.