Tire Size Box

295/35R21 vs 295/45R21

295/45R21 compared with 295/35R21

+8.0% diameter, 0.0" width

295/45R21 is 31.45" tall vs 29.13". More than the 3% rule of thumb, so check carefully before switching.

29.1"21" rim4.1"11.6" wide
295/35R21 (solid) compared with 295/45R21 (dashed outline), drawn to scale

With 295/45R21 tires, when your speedometer says 60 mph you are really going

64.8 mph

295/45R21 is +2.32 inches (+8.0%) in overall diameter. That is more than the 3% most shops and makers recommend.

295/35R21295/45R21Difference%
Overall diameter29.13"31.45"+2.32"+8.0%
Section width11.61"11.61"0.00"0.0%
Sidewall height4.06"5.23"+1.16"+28.6%
Circumference91.51"98.81"+7.30"+8.0%
Revolutions per mile692.4641.2−51.1−7.4%

Speedometer difference

If your vehicle came with 295/35R21 and you fit 295/45R21, 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 mph81.0 mph+6.0 mph
80 mph86.4 mph+6.4 mph

Each size on its own

Questions

Which is bigger, 295/35R21 or 295/45R21?
295/45R21 is taller by 2.32 inches (31.45" vs 29.13"). 295/35R21 is the same width.
Can I replace 295/35R21 with 295/45R21?
It is not recommended without checking carefully. The diameter difference is +8.0%, 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 295/45R21 change my speedometer?
When your speedometer reads 60 mph with 295/45R21 fitted (calibrated for 295/35R21), your real speed is 64.8 mph. Your odometer will under-count miles by about 8.0%.
Will 295/45R21 lift my vehicle?
Ride height changes by half the diameter difference: +1.16 inches of ground clearance at the axle.

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