195/75R15 vs 175/80R15
Going from one to the other changes the overall height by -1.9 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 195/75R15 | 175/80R15 | Change |
|---|---|---|---|
| Overall height | 26.5" | 26.0" | -1.9 % |
| Sidewall | 5.76" | 5.51" | -4.3 % |
| Section width | 195 mm | 175 mm | -10.3 % |
| Circumference | 83.3" | 81.8" | -1.9 % |
| Revs per mile | 761 | 775 | +1.9 % |
| Axle height | 13.26" | 13.01" | -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 195/75R15. Fit 175/80R15 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.4 mph | -0.6 |
| 50 mph | 49.1 mph | -0.9 |
| 70 mph | 68.7 mph | -1.3 |
| 90 mph | 88.3 mph | -1.7 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,814 on the road, so it over-counts by 186. At a true 70 mph the first turns 887 times a minute, the second 904.
What drivers reported
195/75R15 carries 2 complaints. Nobody has filed one naming 175/80R15.