TireSizesFinder

235/65R18 vs 245/65R18

245/65R18 is 0.51 in (13.0 mm) taller than 235/65R18, a +1.70% diameter difference. With the speedometer set for 235/65R18, an indicated 60 mph is 61.0 mph on 245/65R18.

Is this a safe swap?

Diameter difference +1.70%: within the ±3% guideline

By overall diameter alone, 245/65R18 falls inside the ±3% range commonly used as a guideline when replacing 235/65R18. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 235/65R18 (30.03 in) vs 245/65R18 (30.54 in)235/65R1830.03 in × 9.25 in245/65R1830.54 in × 9.65 in
Side profile and tread width, drawn to the same scale.
235/65R18 vs 245/65R18 differences
Measurement235/65R18245/65R18Difference% diff
Overall diameter30.03 in (762.7 mm)30.54 in (775.7 mm)+0.51 in (+13.0 mm)+1.70%
Sidewall height6.01 in (152.8 mm)6.27 in (159.3 mm)+0.26 in (+6.5 mm)+4.26%
Section width9.25 in (235.0 mm)9.65 in (245.0 mm)+0.39 in (+10.0 mm)+4.26%
Circumference94.33 in (2,396.1 mm)95.94 in (2,436.9 mm)+1.61 in (+40.8 mm)+1.70%
Revolutions per mile672660−11−1.68%
True speed with the speedometer calibrated for 235/65R18
IndicatedActual on 235/65R18Actual on 245/65R18Difference
30 mph30.0 mph30.5 mph+0.5 mph
60 mph60.0 mph61.0 mph+1.0 mph
75 mph75.0 mph76.3 mph+1.3 mph

Ride-height change: 245/65R18 raises the vehicle by 0.26 in (6.5 mm) at the axle (half the +13.0 mm diameter difference).

245/65R18 is 0.51 in taller than 235/65R18 and 10 mm wider, a 1.70% difference in overall diameter.

With the speedometer calibrated for 235/65R18, an indicated 60 mph is actually 61.0 mph on 245/65R18, and revolutions per mile change from 672 to 660.

Both sizes mount on 18-inch wheels.

Size pages

Other comparisons with 235/65R18

Other comparisons with 245/65R18

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