235/40R16 vs 215/45R16
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 | 235/40R16 | 215/45R16 | Change |
|---|---|---|---|
| Overall height | 23.4" | 23.6" | +0.9 % |
| Sidewall | 3.70" | 3.81" | +2.9 % |
| Section width | 235 mm | 215 mm | -8.5 % |
| Circumference | 73.5" | 74.2" | +0.9 % |
| Revs per mile | 862 | 854 | -0.9 % |
| Axle height | 11.70" | 11.81" | +2.8 mm |
| Approved rim width | 6.5–8.5" | 6–8" | overlap 6.5–8" |
Both are approved on a rim 6.5" to 8" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 235/40R16. Fit 215/45R16 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 | 70.6 mph | +0.6 |
| 90 mph | 90.8 mph | +0.8 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,093 on the road, so it under-counts by 93. At a true 70 mph the first turns 1005 times a minute, the second 996.
What drivers reported
Nobody has filed a complaint naming 235/40R16. 215/45R16 carries 3.