Tire Size Box

265/45R21 vs 265/50R21

265/50R21 compared with 265/45R21

+3.4% diameter, 0.0" width

265/50R21 is 31.43" tall vs 30.39". More than the 3% rule of thumb, so check carefully before switching.

30.4"21" rim4.7"10.4" wide
265/45R21 (solid) compared with 265/50R21 (dashed outline), drawn to scale

With 265/50R21 tires, when your speedometer says 60 mph you are really going

62.1 mph

265/50R21 is +1.04 inches (+3.4%) in overall diameter. That is more than the 3% most shops and makers recommend.

265/45R21265/50R21Difference%
Overall diameter30.39"31.43"+1.04"+3.4%
Section width10.43"10.43"0.00"0.0%
Sidewall height4.69"5.22"+0.52"+11.1%
Circumference95.47"98.75"+3.28"+3.4%
Revolutions per mile663.6641.6−22.0−3.3%

Speedometer difference

If your vehicle came with 265/45R21 and you fit 265/50R21, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.7 mph+0.7 mph
30 mph31.0 mph+1.0 mph
40 mph41.4 mph+1.4 mph
50 mph51.7 mph+1.7 mph
60 mph62.1 mph+2.1 mph
65 mph67.2 mph+2.2 mph
70 mph72.4 mph+2.4 mph
75 mph77.6 mph+2.6 mph
80 mph82.7 mph+2.7 mph

Each size on its own

Questions

Which is bigger, 265/45R21 or 265/50R21?
265/50R21 is taller by 1.04 inches (31.43" vs 30.39"). 265/45R21 is the same width.
Can I replace 265/45R21 with 265/50R21?
It is not recommended without checking carefully. The diameter difference is +3.4%, 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 265/50R21 change my speedometer?
When your speedometer reads 60 mph with 265/50R21 fitted (calibrated for 265/45R21), your real speed is 62.1 mph. Your odometer will under-count miles by about 3.4%.
Will 265/50R21 lift my vehicle?
Ride height changes by half the diameter difference: +0.52 inches of ground clearance at the axle.

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