165/80R14 vs 175/75R14
Going from one to the other changes the overall height by -0.2 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 165/80R14 | 175/75R14 | Change |
|---|---|---|---|
| Overall height | 24.4" | 24.3" | -0.2 % |
| Sidewall | 5.20" | 5.17" | -0.6 % |
| Section width | 165 mm | 175 mm | +6.1 % |
| Circumference | 76.6" | 76.4" | -0.2 % |
| Revs per mile | 827 | 829 | +0.2 % |
| Axle height | 12.20" | 12.17" | -0.8 mm |
| Approved rim width | 4.5–6" | 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 165/80R14. Fit 175/75R14 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.9 mph | -0.1 |
| 50 mph | 49.9 mph | -0.1 |
| 70 mph | 69.8 mph | -0.2 |
| 90 mph | 89.8 mph | -0.2 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,976 on the road, so it over-counts by 24. At a true 70 mph the first turns 965 times a minute, the second 967.