195/75R17 vs 175/80R17
Going from one to the other changes the overall height by -1.7 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 195/75R17 | 175/80R17 | Change |
|---|---|---|---|
| Overall height | 28.5" | 28.0" | -1.7 % |
| Sidewall | 5.76" | 5.51" | -4.3 % |
| Section width | 195 mm | 175 mm | -10.3 % |
| Circumference | 89.6" | 88.0" | -1.7 % |
| Revs per mile | 707 | 720 | +1.7 % |
| Axle height | 14.26" | 14.01" | -6.3 mm |
| Approved rim width | 5.5–7" | 5–6" | overlap 5.5–6" |
Both are approved on a rim 5.5" to 6" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 195/75R17. Fit 175/80R17 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.5 mph | -0.5 |
| 50 mph | 49.1 mph | -0.9 |
| 70 mph | 68.8 mph | -1.2 |
| 90 mph | 88.4 mph | -1.6 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,827 on the road, so it over-counts by 173. At a true 70 mph the first turns 825 times a minute, the second 840.