245/80R16 vs 235/85R16
Going from one to the other changes the overall height by +0.9 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 245/80R16 | 235/85R16 | Change |
|---|---|---|---|
| Overall height | 31.4" | 31.7" | +0.9 % |
| Sidewall | 7.72" | 7.86" | +1.9 % |
| Section width | 245 mm | 235 mm | -4.1 % |
| Circumference | 98.7" | 99.7" | +0.9 % |
| Revs per mile | 642 | 636 | -0.9 % |
| Axle height | 15.72" | 15.86" | +3.8 mm |
| Approved rim width | 7–9" | 6.5–8.5" | overlap 7–8.5" |
Both are approved on a rim 7" 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 245/80R16. Fit 235/85R16 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.3 mph | +0.3 |
| 50 mph | 50.5 mph | +0.5 |
| 70 mph | 70.7 mph | +0.7 |
| 90 mph | 90.8 mph | +0.8 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,094 on the road, so it under-counts by 94. At a true 70 mph the first turns 749 times a minute, the second 742.
What drivers reported
Nobody has filed a complaint naming 245/80R16. 235/85R16 carries 119.