Tire Size Box

345/25R19 vs 345/30R19

345/30R19 compared with 345/25R19

+5.3% diameter, 0.0" width

345/30R19 is 27.15" tall vs 25.79". More than the 3% rule of thumb, so check carefully before switching.

25.8"19" rim3.4"13.6" wide
345/25R19 (solid) compared with 345/30R19 (dashed outline), drawn to scale

With 345/30R19 tires, when your speedometer says 60 mph you are really going

63.2 mph

345/30R19 is +1.36 inches (+5.3%) in overall diameter. That is more than the 3% most shops and makers recommend.

345/25R19345/30R19Difference%
Overall diameter25.79"27.15"+1.36"+5.3%
Section width13.58"13.58"0.00"0.0%
Sidewall height3.40"4.07"+0.68"+20.0%
Circumference81.03"85.29"+4.27"+5.3%
Revolutions per mile782.0742.9−39.1−5.0%

Speedometer difference

If your vehicle came with 345/25R19 and you fit 345/30R19, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.1 mph+1.1 mph
30 mph31.6 mph+1.6 mph
40 mph42.1 mph+2.1 mph
50 mph52.6 mph+2.6 mph
60 mph63.2 mph+3.2 mph
65 mph68.4 mph+3.4 mph
70 mph73.7 mph+3.7 mph
75 mph78.9 mph+3.9 mph
80 mph84.2 mph+4.2 mph

Each size on its own

Questions

Which is bigger, 345/25R19 or 345/30R19?
345/30R19 is taller by 1.36 inches (27.15" vs 25.79"). 345/25R19 is the same width.
Can I replace 345/25R19 with 345/30R19?
It is not recommended without checking carefully. The diameter difference is +5.3%, 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 345/30R19 change my speedometer?
When your speedometer reads 60 mph with 345/30R19 fitted (calibrated for 345/25R19), your real speed is 63.2 mph. Your odometer will under-count miles by about 5.3%.
Will 345/30R19 lift my vehicle?
Ride height changes by half the diameter difference: +0.68 inches of ground clearance at the axle.

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