Correction Factors for Other Tire Sizes

To calculate ground speeds for tractors equipped with rear tires other than 16.9-30, R1 tires, multiply the ground speeds shown for the 16.9-30, R1 tires in Transmission Ground Speed Estimates report for correct transmission in this section by the correction factor for the appropriate tire found in the table below.

Example: B-2 at 2400 engine rpm with 16.9-24 R1 tires.

4.36 mph (7.02 km/h) x 0.90 = 3.92 mph (6.32 km/h)

Tire Size	Correction Factor
21.5L-16.1 R3	0.74
16.9-24 R4	0.87
16.9-24 R3	0.88
19.5L-24 R4	0.88
16.9-24 R1	0.90
13.6-28 R1	0.90
14.9-28 R1	0.92
16.9-28 R1	0.97
18.4-30 R1	1.04
15.5-38 R1	1.07
9.5L-48 R1	1.17

NOTE: Speed and correction factor information above is based on rolling circumference information from Firestone Farm Tire Data Book. Rolling circumference dimensions for “like” size tires vary by manufacturer.