Tire Size Box

295/40R20 vs 295/50R20

295/50R20 compared with 295/40R20

+7.9% diameter, 0.0" width

295/50R20 is 31.61" tall vs 29.29". More than the 3% rule of thumb, so check carefully before switching.

29.3"20" rim4.6"11.6" wide
295/40R20 (solid) compared with 295/50R20 (dashed outline), drawn to scale

With 295/50R20 tires, when your speedometer says 60 mph you are really going

64.8 mph

295/50R20 is +2.32 inches (+7.9%) in overall diameter. That is more than the 3% most shops and makers recommend.

295/40R20295/50R20Difference%
Overall diameter29.29"31.61"+2.32"+7.9%
Section width11.61"11.61"0.00"0.0%
Sidewall height4.65"5.81"+1.16"+25.0%
Circumference92.02"99.32"+7.30"+7.9%
Revolutions per mile688.5637.9−50.6−7.3%

Speedometer difference

If your vehicle came with 295/40R20 and you fit 295/50R20, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.6 mph+1.6 mph
30 mph32.4 mph+2.4 mph
40 mph43.2 mph+3.2 mph
50 mph54.0 mph+4.0 mph
60 mph64.8 mph+4.8 mph
65 mph70.2 mph+5.2 mph
70 mph75.6 mph+5.6 mph
75 mph80.9 mph+5.9 mph
80 mph86.3 mph+6.3 mph

Each size on its own

Questions

Which is bigger, 295/40R20 or 295/50R20?
295/50R20 is taller by 2.32 inches (31.61" vs 29.29"). 295/40R20 is the same width.
Can I replace 295/40R20 with 295/50R20?
It is not recommended without checking carefully. The diameter difference is +7.9%, 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 295/50R20 change my speedometer?
When your speedometer reads 60 mph with 295/50R20 fitted (calibrated for 295/40R20), your real speed is 64.8 mph. Your odometer will under-count miles by about 7.9%.
Will 295/50R20 lift my vehicle?
Ride height changes by half the diameter difference: +1.16 inches of ground clearance at the axle.

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