195/45R18 vs 215/45R18
Going from one to the other changes the overall height by +2.8 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 195/45R18 | 215/45R18 | Change |
|---|---|---|---|
| Overall height | 24.9" | 25.6" | +2.8 % |
| Sidewall | 3.45" | 3.81" | +10.3 % |
| Section width | 195 mm | 215 mm | +10.3 % |
| Circumference | 78.3" | 80.5" | +2.8 % |
| Revs per mile | 810 | 787 | -2.8 % |
| Axle height | 12.45" | 12.81" | +9.0 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 195/45R18. Fit 215/45R18 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.9 mph | +0.9 |
| 50 mph | 51.4 mph | +1.4 |
| 70 mph | 72.0 mph | +2.0 |
| 90 mph | 92.6 mph | +2.6 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,284 on the road, so it under-counts by 284. At a true 70 mph the first turns 945 times a minute, the second 918.
What drivers reported
Nobody has filed a complaint naming 195/45R18. 215/45R18 carries 5.