Tire Size Box

305/30R20 vs 295/35R20

295/35R20 compared with 305/30R20

+3.4% diameter, −0.4" width

295/35R20 is 28.13" tall vs 27.20". More than the 3% rule of thumb, so check carefully before switching.

27.2"20" rim3.6"12.0" wide
305/30R20 (solid) compared with 295/35R20 (dashed outline), drawn to scale

With 295/35R20 tires, when your speedometer says 60 mph you are really going

62.0 mph

295/35R20 is +0.93 inches (+3.4%) in overall diameter. That is more than the 3% most shops and makers recommend.

305/30R20295/35R20Difference%
Overall diameter27.20"28.13"+0.93"+3.4%
Section width12.01"11.61"−0.39"−3.3%
Sidewall height3.60"4.06"+0.46"+12.8%
Circumference85.47"88.37"+2.91"+3.4%
Revolutions per mile741.3717.0−24.4−3.3%

Speedometer difference

If your vehicle came with 305/30R20 and you fit 295/35R20, 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, 305/30R20 or 295/35R20?
295/35R20 is taller by 0.93 inches (28.13" vs 27.20"). 305/30R20 is wider by 0.39 inches.
Can I replace 305/30R20 with 295/35R20?
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 295/35R20 change my speedometer?
When your speedometer reads 60 mph with 295/35R20 fitted (calibrated for 305/30R20), your real speed is 62.0 mph. Your odometer will under-count miles by about 3.4%.
Will 295/35R20 lift my vehicle?
Ride height changes by half the diameter difference: +0.46 inches of ground clearance at the axle.

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