225/80R17 vs 245/70R17
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 | 225/80R17 | 245/70R17 | Change |
|---|---|---|---|
| Overall height | 31.2" | 30.5" | -2.1 % |
| Sidewall | 7.09" | 6.75" | -4.7 % |
| Section width | 225 mm | 245 mm | +8.9 % |
| Circumference | 97.9" | 95.8" | -2.1 % |
| Revs per mile | 647 | 661 | +2.1 % |
| Axle height | 15.59" | 15.25" | -8.5 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 245/70R17 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 9,785 on the road, so it over-counts by 215. At a true 70 mph the first turns 755 times a minute, the second 771.
What drivers reported
Nobody has filed a complaint naming 225/80R17. 245/70R17 carries 43.