Tire Size Box

305/55R19 vs 305/65R19

305/65R19 compared with 305/55R19

+7.5% diameter, 0.0" width

305/65R19 is 34.61" tall vs 32.21". More than the 3% rule of thumb, so check carefully before switching.

32.2"19" rim6.6"12.0" wide
305/55R19 (solid) compared with 305/65R19 (dashed outline), drawn to scale

With 305/65R19 tires, when your speedometer says 60 mph you are really going

64.5 mph

305/65R19 is +2.40 inches (+7.5%) in overall diameter. That is more than the 3% most shops and makers recommend.

305/55R19305/65R19Difference%
Overall diameter32.21"34.61"+2.40"+7.5%
Section width12.01"12.01"0.00"0.0%
Sidewall height6.60"7.81"+1.20"+18.2%
Circumference101.19"108.73"+7.54"+7.5%
Revolutions per mile626.2582.7−43.4−6.9%

Speedometer difference

If your vehicle came with 305/55R19 and you fit 305/65R19, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.5 mph+1.5 mph
30 mph32.2 mph+2.2 mph
40 mph43.0 mph+3.0 mph
50 mph53.7 mph+3.7 mph
60 mph64.5 mph+4.5 mph
65 mph69.8 mph+4.8 mph
70 mph75.2 mph+5.2 mph
75 mph80.6 mph+5.6 mph
80 mph86.0 mph+6.0 mph

Each size on its own

Questions

Which is bigger, 305/55R19 or 305/65R19?
305/65R19 is taller by 2.40 inches (34.61" vs 32.21"). 305/55R19 is the same width.
Can I replace 305/55R19 with 305/65R19?
It is not recommended without checking carefully. The diameter difference is +7.5%, 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 305/65R19 change my speedometer?
When your speedometer reads 60 mph with 305/65R19 fitted (calibrated for 305/55R19), your real speed is 64.5 mph. Your odometer will under-count miles by about 7.5%.
Will 305/65R19 lift my vehicle?
Ride height changes by half the diameter difference: +1.20 inches of ground clearance at the axle.

Other comparisons