175/80R14 vs 175/75R14
Going from one to the other changes the overall height by -2.8 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 175/80R14 | 175/75R14 | Change |
|---|---|---|---|
| Overall height | 25.0" | 24.3" | -2.8 % |
| Sidewall | 5.51" | 5.17" | -6.3 % |
| Section width | 175 mm | 175 mm | 0.0 % |
| Circumference | 78.6" | 76.4" | -2.8 % |
| Revs per mile | 806 | 829 | +2.8 % |
| Axle height | 12.51" | 12.17" | -8.8 mm |
| Approved rim width | 5–6" | 5–6" | overlap 5–6" |
Both are approved on a rim 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 175/80R14. Fit 175/75R14 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.2 mph | -0.8 |
| 50 mph | 48.6 mph | -1.4 |
| 70 mph | 68.1 mph | -1.9 |
| 90 mph | 87.5 mph | -2.5 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,725 on the road, so it over-counts by 275. At a true 70 mph the first turns 940 times a minute, the second 967.
What drivers reported
175/80R14 carries 2 complaints. Nobody has filed one naming 175/75R14.