275/70R24.5 vs 275/75R24.5
Going from one to the other changes the overall height by +2.7 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 275/70R24.5 | 275/75R24.5 | Change |
|---|---|---|---|
| Overall height | 39.7" | 40.7" | +2.7 % |
| Sidewall | 7.58" | 8.12" | +7.1 % |
| Section width | 275 mm | 275 mm | 0.0 % |
| Circumference | 124.6" | 128.0" | +2.7 % |
| Revs per mile | 509 | 495 | -2.7 % |
| Axle height | 19.83" | 20.37" | +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 275/70R24.5. Fit 275/75R24.5 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.8 mph | +0.8 |
| 50 mph | 51.4 mph | +1.4 |
| 70 mph | 71.9 mph | +1.9 |
| 90 mph | 92.5 mph | +2.5 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,273 on the road, so it under-counts by 273. At a true 70 mph the first turns 593 times a minute, the second 578.
What drivers reported
Nobody has filed a complaint naming 275/70R24.5. 275/75R24.5 carries 1.