TireSizesFinder

245/70R16 vs 235/60R18

235/60R18 is 0.40 in (10.2 mm) shorter than 245/70R16, a −1.36% diameter difference. With the speedometer set for 245/70R16, an indicated 60 mph is 59.2 mph on 235/60R18.

Is this a safe swap?

Diameter difference −1.36%: within the ±3% guideline

By overall diameter alone, 235/60R18 falls inside the ±3% range commonly used as a guideline when replacing 245/70R16. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 245/70R16 (29.50 in) vs 235/60R18 (29.10 in)245/70R1629.50 in × 9.65 in235/60R1829.10 in × 9.25 in
Side profile and tread width, drawn to the same scale.
245/70R16 vs 235/60R18 differences
Measurement245/70R16235/60R18Difference% diff
Overall diameter29.50 in (749.4 mm)29.10 in (739.2 mm)−0.40 in (−10.2 mm)−1.36%
Sidewall height6.75 in (171.5 mm)5.55 in (141.0 mm)−1.20 in (−30.5 mm)−17.78%
Section width9.65 in (245.0 mm)9.25 in (235.0 mm)−0.39 in (−10.0 mm)−4.08%
Circumference92.69 in (2,354.3 mm)91.43 in (2,322.3 mm)−1.26 in (−32.0 mm)−1.36%
Revolutions per mile684693+9+1.38%
True speed with the speedometer calibrated for 245/70R16
IndicatedActual on 245/70R16Actual on 235/60R18Difference
30 mph30.0 mph29.6 mph−0.4 mph
60 mph60.0 mph59.2 mph−0.8 mph
75 mph75.0 mph74.0 mph−1.0 mph

Ride-height change: 235/60R18 lowers the vehicle by 0.20 in (5.1 mm) at the axle (half the −10.2 mm diameter difference).

235/60R18 is 0.40 in shorter than 245/70R16 and 10 mm narrower, a 1.36% difference in overall diameter.

With the speedometer calibrated for 245/70R16, an indicated 60 mph is actually 59.2 mph on 235/60R18, and revolutions per mile change from 684 to 693.

235/60R18 mounts on a 18-inch wheel, a plus-2 fitment from the 16-inch wheel of 245/70R16.

Size pages

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Source: Calculated from standard tire geometry formulas. Verified . How these numbers are calculated.