225/70R17 vs 205/75R17
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 | 225/70R17 | 205/75R17 | Change |
|---|---|---|---|
| Overall height | 29.4" | 29.1" | -1.0 % |
| Sidewall | 6.20" | 6.05" | -2.4 % |
| Section width | 225 mm | 205 mm | -8.9 % |
| Circumference | 92.4" | 91.4" | -1.0 % |
| Revs per mile | 686 | 693 | +1.0 % |
| Axle height | 14.70" | 14.55" | -3.8 mm |
| Approved rim width | 6–8.5" | 5.5–7.5" | overlap 6–7.5" |
Both are approved on a rim 6" to 7.5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 225/70R17. Fit 205/75R17 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 9,900 on the road, so it over-counts by 100. At a true 70 mph the first turns 800 times a minute, the second 808.
What drivers reported
225/70R17 carries 8 complaints. Nobody has filed one naming 205/75R17.