275/70R22.5 vs 275/65R22.5
Going from one to the other changes the overall height by -2.9 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 275/70R22.5 | 275/65R22.5 | Change |
|---|---|---|---|
| Overall height | 37.7" | 36.6" | -2.9 % |
| Sidewall | 7.58" | 7.04" | -7.1 % |
| Section width | 275 mm | 275 mm | 0.0 % |
| Circumference | 118.3" | 114.9" | -2.9 % |
| Revs per mile | 536 | 551 | +2.9 % |
| Axle height | 18.83" | 18.29" | -13.8 mm |
| Approved rim width | 7.5–10" | 7.5–10" | overlap 7.5–10" |
Both are approved on a rim 7.5" to 10" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 275/70R22.5. Fit 275/65R22.5 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.1 mph | -0.9 |
| 50 mph | 48.6 mph | -1.4 |
| 70 mph | 68.0 mph | -2.0 |
| 90 mph | 87.4 mph | -2.6 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,712 on the road, so it over-counts by 288. At a true 70 mph the first turns 625 times a minute, the second 643.
What drivers reported
275/70R22.5 carries 20 complaints. Nobody has filed one naming 275/65R22.5.