195/40R18 vs 215/35R18
Going from one to the other changes the overall height by -0.9 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 195/40R18 | 215/35R18 | Change |
|---|---|---|---|
| Overall height | 24.1" | 23.9" | -0.9 % |
| Sidewall | 3.07" | 2.96" | -3.5 % |
| Section width | 195 mm | 215 mm | +10.3 % |
| Circumference | 75.8" | 75.2" | -0.9 % |
| Revs per mile | 835 | 843 | +0.9 % |
| Axle height | 12.07" | 11.96" | -2.8 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 195/40R18. Fit 215/35R18 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.7 mph | -0.3 |
| 50 mph | 49.6 mph | -0.4 |
| 70 mph | 69.4 mph | -0.6 |
| 90 mph | 89.2 mph | -0.8 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,910 on the road, so it over-counts by 90. At a true 70 mph the first turns 975 times a minute, the second 983.
What drivers reported
Nobody has filed a complaint naming 195/40R18. 215/35R18 carries 2.