135/80R16 vs 135/75R16
Going from one to the other changes the overall height by -2.2 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 135/80R16 | 135/75R16 | Change |
|---|---|---|---|
| Overall height | 24.5" | 24.0" | -2.2 % |
| Sidewall | 4.25" | 3.99" | -6.3 % |
| Section width | 135 mm | 135 mm | 0.0 % |
| Circumference | 77.0" | 75.3" | -2.2 % |
| Revs per mile | 823 | 841 | +2.2 % |
| Axle height | 12.25" | 11.99" | -6.8 mm |
| Approved rim width | 3.5–5" | 3.5–5" | overlap 3.5–5" |
Both are approved on a rim 3.5" to 5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 135/80R16. Fit 135/75R16 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.3 mph | -0.7 |
| 50 mph | 48.9 mph | -1.1 |
| 70 mph | 68.5 mph | -1.5 |
| 90 mph | 88.0 mph | -2.0 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,783 on the road, so it over-counts by 217. At a true 70 mph the first turns 960 times a minute, the second 982.