Tire Size Box

345/35R22 vs 345/40R22

345/40R22 compared with 345/35R22

+4.3% diameter, 0.0" width

345/40R22 is 32.87" tall vs 31.51". More than the 3% rule of thumb, so check carefully before switching.

31.5"22" rim4.8"13.6" wide
345/35R22 (solid) compared with 345/40R22 (dashed outline), drawn to scale

With 345/40R22 tires, when your speedometer says 60 mph you are really going

62.6 mph

345/40R22 is +1.36 inches (+4.3%) in overall diameter. That is more than the 3% most shops and makers recommend.

345/35R22345/40R22Difference%
Overall diameter31.51"32.87"+1.36"+4.3%
Section width13.58"13.58"0.00"0.0%
Sidewall height4.75"5.43"+0.68"+14.3%
Circumference98.98"103.25"+4.27"+4.3%
Revolutions per mile640.1613.6−26.5−4.1%

Speedometer difference

If your vehicle came with 345/35R22 and you fit 345/40R22, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.9 mph+0.9 mph
30 mph31.3 mph+1.3 mph
40 mph41.7 mph+1.7 mph
50 mph52.2 mph+2.2 mph
60 mph62.6 mph+2.6 mph
65 mph67.8 mph+2.8 mph
70 mph73.0 mph+3.0 mph
75 mph78.2 mph+3.2 mph
80 mph83.4 mph+3.4 mph

Each size on its own

Questions

Which is bigger, 345/35R22 or 345/40R22?
345/40R22 is taller by 1.36 inches (32.87" vs 31.51"). 345/35R22 is the same width.
Can I replace 345/35R22 with 345/40R22?
It is not recommended without checking carefully. The diameter difference is +4.3%, 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 345/40R22 change my speedometer?
When your speedometer reads 60 mph with 345/40R22 fitted (calibrated for 345/35R22), your real speed is 62.6 mph. Your odometer will under-count miles by about 4.3%.
Will 345/40R22 lift my vehicle?
Ride height changes by half the diameter difference: +0.68 inches of ground clearance at the axle.

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