Tire Size Box

315/30R22 vs 305/35R22

305/35R22 compared with 315/30R22

+3.3% diameter, −0.4" width

305/35R22 is 30.41" tall vs 29.44". More than the 3% rule of thumb, so check carefully before switching.

29.4"22" rim3.7"12.4" wide
315/30R22 (solid) compared with 305/35R22 (dashed outline), drawn to scale

With 305/35R22 tires, when your speedometer says 60 mph you are really going

62.0 mph

305/35R22 is +0.96 inches (+3.3%) in overall diameter. That is more than the 3% most shops and makers recommend.

315/30R22305/35R22Difference%
Overall diameter29.44"30.41"+0.96"+3.3%
Section width12.40"12.01"−0.39"−3.2%
Sidewall height3.72"4.20"+0.48"+13.0%
Circumference92.49"95.52"+3.03"+3.3%
Revolutions per mile685.0663.3−21.7−3.2%

Speedometer difference

If your vehicle came with 315/30R22 and you fit 305/35R22, 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 mph41.3 mph+1.3 mph
50 mph51.6 mph+1.6 mph
60 mph62.0 mph+2.0 mph
65 mph67.1 mph+2.1 mph
70 mph72.3 mph+2.3 mph
75 mph77.5 mph+2.5 mph
80 mph82.6 mph+2.6 mph

Each size on its own

Questions

Which is bigger, 315/30R22 or 305/35R22?
305/35R22 is taller by 0.96 inches (30.41" vs 29.44"). 315/30R22 is wider by 0.39 inches.
Can I replace 315/30R22 with 305/35R22?
It is not recommended without checking carefully. The diameter difference is +3.3%, 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 305/35R22 change my speedometer?
When your speedometer reads 60 mph with 305/35R22 fitted (calibrated for 315/30R22), your real speed is 62.0 mph. Your odometer will under-count miles by about 3.3%.
Will 305/35R22 lift my vehicle?
Ride height changes by half the diameter difference: +0.48 inches of ground clearance at the axle.

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