195/50R18 vs 215/45R18
Going from one to the other changes the overall height by -0.2 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 195/50R18 | 215/45R18 | Change |
|---|---|---|---|
| Overall height | 25.7" | 25.6" | -0.2 % |
| Sidewall | 3.84" | 3.81" | -0.8 % |
| Section width | 195 mm | 215 mm | +10.3 % |
| Circumference | 80.7" | 80.5" | -0.2 % |
| Revs per mile | 785 | 787 | +0.2 % |
| Axle height | 12.84" | 12.81" | -0.8 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 195/50R18. Fit 215/45R18 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.9 mph | -0.1 |
| 50 mph | 49.9 mph | -0.1 |
| 70 mph | 69.8 mph | -0.2 |
| 90 mph | 89.8 mph | -0.2 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,977 on the road, so it over-counts by 23. At a true 70 mph the first turns 916 times a minute, the second 918.
What drivers reported
Nobody has filed a complaint naming 195/50R18. 215/45R18 carries 5.