Tire Size Box

235/85R16 vs 265/70R17

265/70R17 compared with 235/85R16

−0.4% diameter, +1.2" width

265/70R17 is 31.61" tall vs 31.73". Within the 3% rule, so usually interchangeable.

31.7"16" rim7.9"9.3" wide
235/85R16 (solid) compared with 265/70R17 (dashed outline), drawn to scale

With 265/70R17 tires, when your speedometer says 60 mph you are really going

59.8 mph

265/70R17 is −0.12 inches (−0.4%) in overall diameter. That is within the 3% most shops and makers allow.

235/85R16265/70R17Difference%
Overall diameter31.73"31.61"−0.12"−0.4%
Section width9.25"10.43"+1.18"+12.8%
Sidewall height7.86"7.30"−0.56"−7.1%
Circumference99.68"99.29"−0.38"−0.4%
Revolutions per mile635.6638.1+2.5+0.4%

Speedometer difference

If your vehicle came with 235/85R16 and you fit 265/70R17, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph19.9 mph−0.1 mph
30 mph29.9 mph−0.1 mph
40 mph39.8 mph−0.2 mph
50 mph49.8 mph−0.2 mph
60 mph59.8 mph−0.2 mph
65 mph64.7 mph−0.3 mph
70 mph69.7 mph−0.3 mph
75 mph74.7 mph−0.3 mph
80 mph79.7 mph−0.3 mph

Each size on its own

Questions

Which is bigger, 235/85R16 or 265/70R17?
235/85R16 is taller by 0.12 inches (31.73" vs 31.61"). 265/70R17 is wider by 1.18 inches.
Can I replace 235/85R16 with 265/70R17?
Usually, yes. The diameter difference is −0.4%, inside the 3% rule of thumb most tire shops use. Check that the wider or taller tire clears your suspension and fenders, and that its load index meets your placard.
How much will 265/70R17 change my speedometer?
When your speedometer reads 60 mph with 265/70R17 fitted (calibrated for 235/85R16), your real speed is 59.8 mph. Your odometer will over-count miles by about 0.4%.
Will 265/70R17 lift my vehicle?
Ride height changes by half the diameter difference: −0.06 inches of ground clearance at the axle.

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