Tire Size Box

235/45R19 vs 235/55R19

235/55R19 compared with 235/45R19

+6.8% diameter, 0.0" width

235/55R19 is 29.18" tall vs 27.33". More than the 3% rule of thumb, so check carefully before switching.

27.3"19" rim4.2"9.3" wide
235/45R19 (solid) compared with 235/55R19 (dashed outline), drawn to scale

With 235/55R19 tires, when your speedometer says 60 mph you are really going

64.1 mph

235/55R19 is +1.85 inches (+6.8%) in overall diameter. That is more than the 3% most shops and makers recommend.

235/45R19235/55R19Difference%
Overall diameter27.33"29.18"+1.85"+6.8%
Section width9.25"9.25"0.00"0.0%
Sidewall height4.16"5.09"+0.93"+22.2%
Circumference85.85"91.66"+5.81"+6.8%
Revolutions per mile738.0691.2−46.8−6.3%

Speedometer difference

If your vehicle came with 235/45R19 and you fit 235/55R19, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.4 mph+1.4 mph
30 mph32.0 mph+2.0 mph
40 mph42.7 mph+2.7 mph
50 mph53.4 mph+3.4 mph
60 mph64.1 mph+4.1 mph
65 mph69.4 mph+4.4 mph
70 mph74.7 mph+4.7 mph
75 mph80.1 mph+5.1 mph
80 mph85.4 mph+5.4 mph

Each size on its own

Questions

Which is bigger, 235/45R19 or 235/55R19?
235/55R19 is taller by 1.85 inches (29.18" vs 27.33"). 235/45R19 is the same width.
Can I replace 235/45R19 with 235/55R19?
It is not recommended without checking carefully. The diameter difference is +6.8%, 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 235/55R19 change my speedometer?
When your speedometer reads 60 mph with 235/55R19 fitted (calibrated for 235/45R19), your real speed is 64.1 mph. Your odometer will under-count miles by about 6.8%.
Will 235/55R19 lift my vehicle?
Ride height changes by half the diameter difference: +0.93 inches of ground clearance at the axle.

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