Tire Size Box

355/35R22 vs 345/40R22

345/40R22 compared with 355/35R22

+3.4% diameter, −0.4" width

345/40R22 is 32.87" tall vs 31.78". More than the 3% rule of thumb, so check carefully before switching.

31.8"22" rim4.9"14.0" wide
355/35R22 (solid) compared with 345/40R22 (dashed outline), drawn to scale

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

62.0 mph

345/40R22 is +1.08 inches (+3.4%) in overall diameter. That is more than the 3% most shops and makers recommend.

355/35R22345/40R22Difference%
Overall diameter31.78"32.87"+1.08"+3.4%
Section width13.98"13.58"−0.39"−2.8%
Sidewall height4.89"5.43"+0.54"+11.1%
Circumference99.85"103.25"+3.40"+3.4%
Revolutions per mile634.5613.6−20.9−3.3%

Speedometer difference

If your vehicle came with 355/35R22 and you fit 345/40R22, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.7 mph+0.7 mph
30 mph31.0 mph+1.0 mph
40 mph41.4 mph+1.4 mph
50 mph51.7 mph+1.7 mph
60 mph62.0 mph+2.0 mph
65 mph67.2 mph+2.2 mph
70 mph72.4 mph+2.4 mph
75 mph77.6 mph+2.6 mph
80 mph82.7 mph+2.7 mph

Each size on its own

Questions

Which is bigger, 355/35R22 or 345/40R22?
345/40R22 is taller by 1.08 inches (32.87" vs 31.78"). 355/35R22 is wider by 0.39 inches.
Can I replace 355/35R22 with 345/40R22?
It is not recommended without checking carefully. The diameter difference is +3.4%, 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 355/35R22), your real speed is 62.0 mph. Your odometer will under-count miles by about 3.4%.
Will 345/40R22 lift my vehicle?
Ride height changes by half the diameter difference: +0.54 inches of ground clearance at the axle.

Other comparisons