235/80R15 vs 225/80R15
Going from one to the other changes the overall height by -2.1 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 235/80R15 | 225/80R15 | Change |
|---|---|---|---|
| Overall height | 29.8" | 29.2" | -2.1 % |
| Sidewall | 7.40" | 7.09" | -4.3 % |
| Section width | 235 mm | 225 mm | -4.3 % |
| Circumference | 93.6" | 91.7" | -2.1 % |
| Revs per mile | 677 | 691 | +2.1 % |
| Axle height | 14.90" | 14.59" | -8.0 mm |
| Approved rim width | 6.5–8.5" | 6–8.5" | overlap 6.5–8.5" |
Both are approved on a rim 6.5" to 8.5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 235/80R15. Fit 225/80R15 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.4 mph | -0.6 |
| 50 mph | 48.9 mph | -1.1 |
| 70 mph | 68.5 mph | -1.5 |
| 90 mph | 88.1 mph | -1.9 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,789 on the road, so it over-counts by 211. At a true 70 mph the first turns 789 times a minute, the second 807.
What drivers reported
235/80R15 carries 1 complaints. Nobody has filed one naming 225/80R15.