Tire Size Box

335/35R18 vs 335/45R18

335/45R18 compared with 335/35R18

+9.7% diameter, 0.0" width

335/45R18 is 29.87" tall vs 27.23". More than the 3% rule of thumb, so check carefully before switching.

27.2"18" rim4.6"13.2" wide
335/35R18 (solid) compared with 335/45R18 (dashed outline), drawn to scale

With 335/45R18 tires, when your speedometer says 60 mph you are really going

65.8 mph

335/45R18 is +2.64 inches (+9.7%) in overall diameter. That is more than the 3% most shops and makers recommend.

335/35R18335/45R18Difference%
Overall diameter27.23"29.87"+2.64"+9.7%
Section width13.19"13.19"0.00"0.0%
Sidewall height4.62"5.94"+1.32"+28.6%
Circumference85.55"93.84"+8.29"+9.7%
Revolutions per mile740.6675.2−65.4−8.8%

Speedometer difference

If your vehicle came with 335/35R18 and you fit 335/45R18, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.9 mph+1.9 mph
30 mph32.9 mph+2.9 mph
40 mph43.9 mph+3.9 mph
50 mph54.8 mph+4.8 mph
60 mph65.8 mph+5.8 mph
65 mph71.3 mph+6.3 mph
70 mph76.8 mph+6.8 mph
75 mph82.3 mph+7.3 mph
80 mph87.7 mph+7.7 mph

Each size on its own

Questions

Which is bigger, 335/35R18 or 335/45R18?
335/45R18 is taller by 2.64 inches (29.87" vs 27.23"). 335/35R18 is the same width.
Can I replace 335/35R18 with 335/45R18?
It is not recommended without checking carefully. The diameter difference is +9.7%, more than the 3% most shops and makers allow. It will throw off the speedometer and may affect ABS, stability control and clearance.
How much will 335/45R18 change my speedometer?
When your speedometer reads 60 mph with 335/45R18 fitted (calibrated for 335/35R18), your real speed is 65.8 mph. Your odometer will under-count miles by about 9.7%.
Will 335/45R18 lift my vehicle?
Ride height changes by half the diameter difference: +1.32 inches of ground clearance at the axle.

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