215/35R15 vs 195/40R15
Going from one to the other changes the overall height by +1.0 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 215/35R15 | 195/40R15 | Change |
|---|---|---|---|
| Overall height | 20.9" | 21.1" | +1.0 % |
| Sidewall | 2.96" | 3.07" | +3.7 % |
| Section width | 215 mm | 195 mm | -9.3 % |
| Circumference | 65.7" | 66.4" | +1.0 % |
| Revs per mile | 964 | 954 | -1.0 % |
| Axle height | 10.46" | 10.57" | +2.8 mm |
| Approved rim width | 6–8" | 5.5–7" | 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 215/35R15. Fit 195/40R15 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.3 mph | +0.3 |
| 50 mph | 50.5 mph | +0.5 |
| 70 mph | 70.7 mph | +0.7 |
| 90 mph | 90.9 mph | +0.9 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,103 on the road, so it under-counts by 103. At a true 70 mph the first turns 1124 times a minute, the second 1113.