175/65R16 vs 155/70R16
Going from one to the other changes the overall height by -1.7 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 175/65R16 | 155/70R16 | Change |
|---|---|---|---|
| Overall height | 25.0" | 24.5" | -1.7 % |
| Sidewall | 4.48" | 4.27" | -4.6 % |
| Section width | 175 mm | 155 mm | -11.4 % |
| Circumference | 78.4" | 77.1" | -1.7 % |
| Revs per mile | 808 | 822 | +1.7 % |
| Axle height | 12.48" | 12.27" | -5.3 mm |
| Approved rim width | 5–6" | 4–5.5" | 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 175/65R16. Fit 155/70R16 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 | 68.8 mph | -1.2 |
| 90 mph | 88.5 mph | -1.5 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,834 on the road, so it over-counts by 166. At a true 70 mph the first turns 943 times a minute, the second 959.