Tire Size Box

185/45R16 vs 185/50R16

185/50R16 compared with 185/45R16

+3.2% diameter, 0.0" width

185/50R16 is 23.28" tall vs 22.56". More than the 3% rule of thumb, so check carefully before switching.

22.6"16" rim3.3"7.3" wide
185/45R16 (solid) compared with 185/50R16 (dashed outline), drawn to scale

With 185/50R16 tires, when your speedometer says 60 mph you are really going

61.9 mph

185/50R16 is +0.73 inches (+3.2%) in overall diameter. That is more than the 3% most shops and makers recommend.

185/45R16185/50R16Difference%
Overall diameter22.56"23.28"+0.73"+3.2%
Section width7.28"7.28"0.00"0.0%
Sidewall height3.28"3.64"+0.36"+11.1%
Circumference70.86"73.15"+2.29"+3.2%
Revolutions per mile894.2866.2−28.0−3.1%

Speedometer difference

If your vehicle came with 185/45R16 and you fit 185/50R16, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.6 mph+0.6 mph
30 mph31.0 mph+1.0 mph
40 mph41.3 mph+1.3 mph
50 mph51.6 mph+1.6 mph
60 mph61.9 mph+1.9 mph
65 mph67.1 mph+2.1 mph
70 mph72.3 mph+2.3 mph
75 mph77.4 mph+2.4 mph
80 mph82.6 mph+2.6 mph

Each size on its own

Questions

Which is bigger, 185/45R16 or 185/50R16?
185/50R16 is taller by 0.73 inches (23.28" vs 22.56"). 185/45R16 is the same width.
Can I replace 185/45R16 with 185/50R16?
It is not recommended without checking carefully. The diameter difference is +3.2%, 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 185/50R16 change my speedometer?
When your speedometer reads 60 mph with 185/50R16 fitted (calibrated for 185/45R16), your real speed is 61.9 mph. Your odometer will under-count miles by about 3.2%.
Will 185/50R16 lift my vehicle?
Ride height changes by half the diameter difference: +0.36 inches of ground clearance at the axle.

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