Tire Size Box

305/40R17 vs 295/45R17

295/45R17 compared with 305/40R17

+3.2% diameter, −0.4" width

295/45R17 is 27.45" tall vs 26.61". More than the 3% rule of thumb, so check carefully before switching.

26.6"17" rim4.8"12.0" wide
305/40R17 (solid) compared with 295/45R17 (dashed outline), drawn to scale

With 295/45R17 tires, when your speedometer says 60 mph you are really going

61.9 mph

295/45R17 is +0.85 inches (+3.2%) in overall diameter. That is more than the 3% most shops and makers recommend.

305/40R17295/45R17Difference%
Overall diameter26.61"27.45"+0.85"+3.2%
Section width12.01"11.61"−0.39"−3.3%
Sidewall height4.80"5.23"+0.42"+8.8%
Circumference83.59"86.25"+2.66"+3.2%
Revolutions per mile758.0734.6−23.4−3.1%

Speedometer difference

If your vehicle came with 305/40R17 and you fit 295/45R17, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.6 mph+0.6 mph
30 mph31.0 mph+1.0 mph
40 mph41.3 mph+1.3 mph
50 mph51.6 mph+1.6 mph
60 mph61.9 mph+1.9 mph
65 mph67.1 mph+2.1 mph
70 mph72.2 mph+2.2 mph
75 mph77.4 mph+2.4 mph
80 mph82.5 mph+2.5 mph

Each size on its own

Questions

Which is bigger, 305/40R17 or 295/45R17?
295/45R17 is taller by 0.85 inches (27.45" vs 26.61"). 305/40R17 is wider by 0.39 inches.
Can I replace 305/40R17 with 295/45R17?
It is not recommended without checking carefully. The diameter difference is +3.2%, 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 295/45R17 change my speedometer?
When your speedometer reads 60 mph with 295/45R17 fitted (calibrated for 305/40R17), your real speed is 61.9 mph. Your odometer will under-count miles by about 3.2%.
Will 295/45R17 lift my vehicle?
Ride height changes by half the diameter difference: +0.42 inches of ground clearance at the axle.

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