225/80R17 vs 245/75R17
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 | 225/80R17 | 245/75R17 | Change |
|---|---|---|---|
| Overall height | 31.2" | 31.5" | +0.9 % |
| Sidewall | 7.09" | 7.23" | +2.1 % |
| Section width | 225 mm | 245 mm | +8.9 % |
| Circumference | 97.9" | 98.9" | +0.9 % |
| Revs per mile | 647 | 641 | -0.9 % |
| Axle height | 15.59" | 15.73" | +3.8 mm |
| Approved rim width | 6–8.5" | 7–9" | overlap 7–8.5" |
Both are approved on a rim 7" to 8.5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 225/80R17. Fit 245/75R17 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 | 70.7 mph | +0.7 |
| 90 mph | 90.9 mph | +0.9 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,095 on the road, so it under-counts by 95. At a true 70 mph the first turns 755 times a minute, the second 748.
What drivers reported
Nobody has filed a complaint naming 225/80R17. 245/75R17 carries 11.