Tire Size Box

285/25R24 vs 285/30R24

285/30R24 compared with 285/25R24

+3.8% diameter, 0.0" width

285/30R24 is 30.73" tall vs 29.61". More than the 3% rule of thumb, so check carefully before switching.

29.6"24" rim2.8"11.2" wide
285/25R24 (solid) compared with 285/30R24 (dashed outline), drawn to scale

With 285/30R24 tires, when your speedometer says 60 mph you are really going

62.3 mph

285/30R24 is +1.12 inches (+3.8%) in overall diameter. That is more than the 3% most shops and makers recommend.

285/25R24285/30R24Difference%
Overall diameter29.61"30.73"+1.12"+3.8%
Section width11.22"11.22"0.00"0.0%
Sidewall height2.81"3.37"+0.56"+20.0%
Circumference93.02"96.55"+3.53"+3.8%
Revolutions per mile681.1656.3−24.9−3.7%

Speedometer difference

If your vehicle came with 285/25R24 and you fit 285/30R24, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.8 mph+0.8 mph
30 mph31.1 mph+1.1 mph
40 mph41.5 mph+1.5 mph
50 mph51.9 mph+1.9 mph
60 mph62.3 mph+2.3 mph
65 mph67.5 mph+2.5 mph
70 mph72.7 mph+2.7 mph
75 mph77.8 mph+2.8 mph
80 mph83.0 mph+3.0 mph

Each size on its own

Questions

Which is bigger, 285/25R24 or 285/30R24?
285/30R24 is taller by 1.12 inches (30.73" vs 29.61"). 285/25R24 is the same width.
Can I replace 285/25R24 with 285/30R24?
It is not recommended without checking carefully. The diameter difference is +3.8%, 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 285/30R24 change my speedometer?
When your speedometer reads 60 mph with 285/30R24 fitted (calibrated for 285/25R24), your real speed is 62.3 mph. Your odometer will under-count miles by about 3.8%.
Will 285/30R24 lift my vehicle?
Ride height changes by half the diameter difference: +0.56 inches of ground clearance at the axle.

Other comparisons