Tire Size Box

205/35R17 vs 205/40R17

205/40R17 compared with 205/35R17

+3.6% diameter, 0.0" width

205/40R17 is 23.46" tall vs 22.65". More than the 3% rule of thumb, so check carefully before switching.

22.6"17" rim2.8"8.1" wide
205/35R17 (solid) compared with 205/40R17 (dashed outline), drawn to scale

With 205/40R17 tires, when your speedometer says 60 mph you are really going

62.1 mph

205/40R17 is +0.81 inches (+3.6%) in overall diameter. That is more than the 3% most shops and makers recommend.

205/35R17205/40R17Difference%
Overall diameter22.65"23.46"+0.81"+3.6%
Section width8.07"8.07"0.00"0.0%
Sidewall height2.82"3.23"+0.40"+14.3%
Circumference71.16"73.69"+2.54"+3.6%
Revolutions per mile890.4859.8−30.6−3.4%

Speedometer difference

If your vehicle came with 205/35R17 and you fit 205/40R17, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.7 mph+0.7 mph
30 mph31.1 mph+1.1 mph
40 mph41.4 mph+1.4 mph
50 mph51.8 mph+1.8 mph
60 mph62.1 mph+2.1 mph
65 mph67.3 mph+2.3 mph
70 mph72.5 mph+2.5 mph
75 mph77.7 mph+2.7 mph
80 mph82.9 mph+2.9 mph

Each size on its own

Questions

Which is bigger, 205/35R17 or 205/40R17?
205/40R17 is taller by 0.81 inches (23.46" vs 22.65"). 205/35R17 is the same width.
Can I replace 205/35R17 with 205/40R17?
It is not recommended without checking carefully. The diameter difference is +3.6%, 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 205/40R17 change my speedometer?
When your speedometer reads 60 mph with 205/40R17 fitted (calibrated for 205/35R17), your real speed is 62.1 mph. Your odometer will under-count miles by about 3.6%.
Will 205/40R17 lift my vehicle?
Ride height changes by half the diameter difference: +0.40 inches of ground clearance at the axle.

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