Tire Size Box

255/25R19 vs 245/30R19

245/30R19 compared with 255/25R19

+3.2% diameter, −0.4" width

245/30R19 is 24.79" tall vs 24.02". More than the 3% rule of thumb, so check carefully before switching.

24.0"19" rim2.5"10.0" wide
255/25R19 (solid) compared with 245/30R19 (dashed outline), drawn to scale

With 245/30R19 tires, when your speedometer says 60 mph you are really going

61.9 mph

245/30R19 is +0.77 inches (+3.2%) in overall diameter. That is more than the 3% most shops and makers recommend.

255/25R19245/30R19Difference%
Overall diameter24.02"24.79"+0.77"+3.2%
Section width10.04"9.65"−0.39"−3.9%
Sidewall height2.51"2.89"+0.38"+15.3%
Circumference75.46"77.87"+2.41"+3.2%
Revolutions per mile839.6813.6−26.0−3.1%

Speedometer difference

If your vehicle came with 255/25R19 and you fit 245/30R19, 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 mph82.6 mph+2.6 mph

Each size on its own

Questions

Which is bigger, 255/25R19 or 245/30R19?
245/30R19 is taller by 0.77 inches (24.79" vs 24.02"). 255/25R19 is wider by 0.39 inches.
Can I replace 255/25R19 with 245/30R19?
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 245/30R19 change my speedometer?
When your speedometer reads 60 mph with 245/30R19 fitted (calibrated for 255/25R19), your real speed is 61.9 mph. Your odometer will under-count miles by about 3.2%.
Will 245/30R19 lift my vehicle?
Ride height changes by half the diameter difference: +0.38 inches of ground clearance at the axle.

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