235/50R17 vs 295/35R18

295/35R18 is 0.12 in (3.1 mm) shorter than 235/50R17, a −0.46% diameter difference. With the speedometer set for 235/50R17, an indicated 60 mph is 59.7 mph on 295/35R18.

Is this a safe swap?

Diameter difference −0.46%: under 1%

By overall diameter alone, 295/35R18 is a near match for 235/50R17; the speedometer changes by less than 1%. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

Side profile and tread width, drawn to the same scale.

235/50R17 vs 295/35R18 differences
Measurement	235/50R17	295/35R18	Difference	% diff
Overall diameter	26.25 in (666.8 mm)	26.13 in (663.7 mm)	−0.12 in (−3.1 mm)	−0.46%
Sidewall height	4.63 in (117.5 mm)	4.06 in (103.3 mm)	−0.56 in (−14.2 mm)	−12.13%
Section width	9.25 in (235.0 mm)	11.61 in (295.0 mm)	+2.36 in (+60.0 mm)	+25.53%
Circumference	82.47 in (2,094.8 mm)	82.09 in (2,085.1 mm)	−0.38 in (−9.7 mm)	−0.46%
Revolutions per mile	768	772	+4	+0.47%

True speed with the speedometer calibrated for 235/50R17
Indicated	Actual on 235/50R17	Actual on 295/35R18	Difference
30 mph	30.0 mph	29.9 mph	−0.1 mph
60 mph	60.0 mph	59.7 mph	−0.3 mph
75 mph	75.0 mph	74.7 mph	−0.3 mph

Ride-height change: 295/35R18 lowers the vehicle by 0.06 in (1.5 mm) at the axle (half the −3.1 mm diameter difference).

295/35R18 is 0.12 in shorter than 235/50R17 and 60 mm wider, a 0.46% difference in overall diameter.

With the speedometer calibrated for 235/50R17, an indicated 60 mph is actually 59.7 mph on 295/35R18, and revolutions per mile change from 768 to 772.

295/35R18 mounts on a 18-inch wheel, a plus-1 fitment from the 17-inch wheel of 235/50R17.

Size pages

Other comparisons with 235/50R17

Other comparisons with 295/35R18

Source: Calculated from standard tire geometry formulas. Verified 2026-09-27. How these numbers are calculated.