335/65R21 vs 355/60R21
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 | 335/65R21 | 355/60R21 | Change |
|---|---|---|---|
| Overall height | 38.1" | 37.8" | -1.0 % |
| Sidewall | 8.57" | 8.39" | -2.2 % |
| Section width | 335 mm | 355 mm | +6.0 % |
| Circumference | 119.8" | 118.7" | -1.0 % |
| Revs per mile | 529 | 534 | +1.0 % |
| Axle height | 19.07" | 18.89" | -4.8 mm |
| Approved rim width | 9.5–12.5" | 10–13" | overlap 10–12.5" |
Both are approved on a rim 10" to 12.5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 335/65R21. Fit 355/60R21 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.7 mph | -0.3 |
| 50 mph | 49.5 mph | -0.5 |
| 70 mph | 69.3 mph | -0.7 |
| 90 mph | 89.1 mph | -0.9 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,902 on the road, so it over-counts by 98. At a true 70 mph the first turns 617 times a minute, the second 623.