135/70R15 vs 135/75R15
Going from one to the other changes the overall height by +2.4 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 135/70R15 | 135/75R15 | Change |
|---|---|---|---|
| Overall height | 22.4" | 23.0" | +2.4 % |
| Sidewall | 3.72" | 3.99" | +7.1 % |
| Section width | 135 mm | 135 mm | 0.0 % |
| Circumference | 70.5" | 72.2" | +2.4 % |
| Revs per mile | 899 | 878 | -2.4 % |
| Axle height | 11.22" | 11.49" | +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 135/70R15. Fit 135/75R15 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.7 mph | +0.7 |
| 50 mph | 51.2 mph | +1.2 |
| 70 mph | 71.7 mph | +1.7 |
| 90 mph | 92.1 mph | +2.1 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,237 on the road, so it under-counts by 237. At a true 70 mph the first turns 1049 times a minute, the second 1024.
What drivers reported
135/70R15 carries 2 complaints. Nobody has filed one naming 135/75R15.