Tire Size Box

195/45R17 vs 185/50R17

185/50R17 compared with 195/45R17

+1.6% diameter, −0.4" width

185/50R17 is 24.28" tall vs 23.91". Within the 3% rule, so usually interchangeable.

23.9"17" rim3.5"7.7" wide
195/45R17 (solid) compared with 185/50R17 (dashed outline), drawn to scale

With 185/50R17 tires, when your speedometer says 60 mph you are really going

60.9 mph

185/50R17 is +0.37 inches (+1.6%) in overall diameter. That is within the 3% most shops and makers allow.

195/45R17185/50R17Difference%
Overall diameter23.91"24.28"+0.37"+1.6%
Section width7.68"7.28"−0.39"−5.1%
Sidewall height3.45"3.64"+0.19"+5.4%
Circumference75.11"76.29"+1.18"+1.6%
Revolutions per mile843.5830.5−13.0−1.5%

Speedometer difference

If your vehicle came with 195/45R17 and you fit 185/50R17, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.3 mph+0.3 mph
30 mph30.5 mph+0.5 mph
40 mph40.6 mph+0.6 mph
50 mph50.8 mph+0.8 mph
60 mph60.9 mph+0.9 mph
65 mph66.0 mph+1.0 mph
70 mph71.1 mph+1.1 mph
75 mph76.2 mph+1.2 mph
80 mph81.3 mph+1.3 mph

Each size on its own

Questions

Which is bigger, 195/45R17 or 185/50R17?
185/50R17 is taller by 0.37 inches (24.28" vs 23.91"). 195/45R17 is wider by 0.39 inches.
Can I replace 195/45R17 with 185/50R17?
Usually, yes. The diameter difference is +1.6%, inside the 3% rule of thumb most tire shops use. Check that the wider or taller tire clears your suspension and fenders, and that its load index meets your placard.
How much will 185/50R17 change my speedometer?
When your speedometer reads 60 mph with 185/50R17 fitted (calibrated for 195/45R17), your real speed is 60.9 mph. Your odometer will under-count miles by about 1.6%.
Will 185/50R17 lift my vehicle?
Ride height changes by half the diameter difference: +0.19 inches of ground clearance at the axle.

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