215/40R20 vs 225/35R20
Going from one to the other changes the overall height by -2.1 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 215/40R20 | 225/35R20 | Change |
|---|---|---|---|
| Overall height | 26.8" | 26.2" | -2.1 % |
| Sidewall | 3.39" | 3.10" | -8.4 % |
| Section width | 215 mm | 225 mm | +4.7 % |
| Circumference | 84.1" | 82.3" | -2.1 % |
| Revs per mile | 753 | 770 | +2.1 % |
| Axle height | 13.39" | 13.10" | -7.3 mm |
| Approved rim width | 6–8" | 6–8.5" | overlap 6–8" |
Both are approved on a rim 6" to 8" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 215/40R20. Fit 225/35R20 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.4 mph | -0.6 |
| 50 mph | 48.9 mph | -1.1 |
| 70 mph | 68.5 mph | -1.5 |
| 90 mph | 88.1 mph | -1.9 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,787 on the road, so it over-counts by 213. At a true 70 mph the first turns 879 times a minute, the second 898.
What drivers reported
Nobody has filed a complaint naming 215/40R20. 225/35R20 carries 2.