155/75R16 vs 175/70R16
Going from one to the other changes the overall height by +2.0 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 155/75R16 | 175/70R16 | Change |
|---|---|---|---|
| Overall height | 25.2" | 25.6" | +2.0 % |
| Sidewall | 4.58" | 4.82" | +5.4 % |
| Section width | 155 mm | 175 mm | +12.9 % |
| Circumference | 79.0" | 80.6" | +2.0 % |
| Revs per mile | 802 | 786 | -2.0 % |
| Axle height | 12.58" | 12.82" | +6.3 mm |
| Approved rim width | 4–5.5" | 5–6" | overlap 5–5.5" |
Both are approved on a rim 5" to 5.5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 155/75R16. Fit 175/70R16 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.6 mph | +0.6 |
| 50 mph | 51.0 mph | +1.0 |
| 70 mph | 71.4 mph | +1.4 |
| 90 mph | 91.8 mph | +1.8 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,196 on the road, so it under-counts by 196. At a true 70 mph the first turns 935 times a minute, the second 917.