Tire Size Box

235/45R15 vs 235/50R15

235/50R15 compared with 235/45R15

+4.0% diameter, 0.0" width

235/50R15 is 24.25" tall vs 23.33". More than the 3% rule of thumb, so check carefully before switching.

23.3"15" rim4.2"9.3" wide
235/45R15 (solid) compared with 235/50R15 (dashed outline), drawn to scale

With 235/50R15 tires, when your speedometer says 60 mph you are really going

62.4 mph

235/50R15 is +0.93 inches (+4.0%) in overall diameter. That is more than the 3% most shops and makers recommend.

235/45R15235/50R15Difference%
Overall diameter23.33"24.25"+0.93"+4.0%
Section width9.25"9.25"0.00"0.0%
Sidewall height4.16"4.63"+0.46"+11.1%
Circumference73.28"76.19"+2.91"+4.0%
Revolutions per mile864.6831.6−33.0−3.8%

Speedometer difference

If your vehicle came with 235/45R15 and you fit 235/50R15, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.8 mph+0.8 mph
30 mph31.2 mph+1.2 mph
40 mph41.6 mph+1.6 mph
50 mph52.0 mph+2.0 mph
60 mph62.4 mph+2.4 mph
65 mph67.6 mph+2.6 mph
70 mph72.8 mph+2.8 mph
75 mph78.0 mph+3.0 mph
80 mph83.2 mph+3.2 mph

Each size on its own

Questions

Which is bigger, 235/45R15 or 235/50R15?
235/50R15 is taller by 0.93 inches (24.25" vs 23.33"). 235/45R15 is the same width.
Can I replace 235/45R15 with 235/50R15?
It is not recommended without checking carefully. The diameter difference is +4.0%, 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 235/50R15 change my speedometer?
When your speedometer reads 60 mph with 235/50R15 fitted (calibrated for 235/45R15), your real speed is 62.4 mph. Your odometer will under-count miles by about 4.0%.
Will 235/50R15 lift my vehicle?
Ride height changes by half the diameter difference: +0.46 inches of ground clearance at the axle.

Other comparisons