245/60R18 vs 265/55R18
Going from one to the other changes the overall height by -0.3 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 245/60R18 | 265/55R18 | Change |
|---|---|---|---|
| Overall height | 29.6" | 29.5" | -0.3 % |
| Sidewall | 5.79" | 5.74" | -0.9 % |
| Section width | 245 mm | 265 mm | +8.2 % |
| Circumference | 92.9" | 92.6" | -0.3 % |
| Revs per mile | 682 | 684 | +0.3 % |
| Axle height | 14.79" | 14.74" | -1.3 mm |
| Approved rim width | 7–9" | 7.5–9.5" | overlap 7.5–9" |
Both are approved on a rim 7.5" to 9" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 245/60R18. Fit 265/55R18 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.9 mph | -0.1 |
| 50 mph | 49.8 mph | -0.2 |
| 70 mph | 69.8 mph | -0.2 |
| 90 mph | 89.7 mph | -0.3 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,967 on the road, so it over-counts by 33. At a true 70 mph the first turns 796 times a minute, the second 798.
What drivers reported
245/60R18 carries 14 complaints. Nobody has filed one naming 265/55R18.