195/70R15 vs 175/75R15
Going from one to the other changes the overall height by -1.6 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 195/70R15 | 175/75R15 | Change |
|---|---|---|---|
| Overall height | 25.7" | 25.3" | -1.6 % |
| Sidewall | 5.37" | 5.17" | -3.8 % |
| Section width | 195 mm | 175 mm | -10.3 % |
| Circumference | 80.9" | 79.6" | -1.6 % |
| Revs per mile | 783 | 796 | +1.6 % |
| Axle height | 12.87" | 12.67" | -5.3 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 195/70R15. Fit 175/75R15 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.5 mph | -0.5 |
| 50 mph | 49.2 mph | -0.8 |
| 70 mph | 68.9 mph | -1.1 |
| 90 mph | 88.6 mph | -1.4 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,839 on the road, so it over-counts by 161. At a true 70 mph the first turns 914 times a minute, the second 929.
What drivers reported
195/70R15 carries 2 complaints. Nobody has filed one naming 175/75R15.