Tire CombinationsIMPORTANT: Avoid excessive drive train wear. Do not mix worn and new tires, bias and radial, or tires of different diameters. With the tire industry converting to metric designations, there are many new terms which can be confusing. To simplify things, tires are placed into groups by their Rolling Circumference Index (RCI) . Rolling circumference is the distance a tire travels in one revolution. Tires with-in a group, regardless of rim size, are the same or nearly the same height. Knowing and understanding RCI and group sizes makes choosing front and rear tire combinations easier. RCI is important for proper MFWD and Independent Link Suspension tractor setup. With both types of front axles, front and rear tires do the work. Since front tires are smaller than rear tires, front tires have to rotate faster to cover the same distance as the rear. Therefore it is important to select the correct size to optimize efficiency and ensure longer tire life. Tractors equipped with MFWD always have front tires that are five group sizes smaller than the rear tire group. Tractors equipped with Independent Link Suspension have a "4" or "5" marking (A) stamped on the right side of front differential housing. This marking identifies axle gear ratio and the difference in tire group size required. The front tire must be from a group that is four or five group sizes smaller than the rear tire group. For example, if the rear tires are group 48, and the front differential is stamped with "5", then the front tires must be group 43. The rim size is of no consequence. Different rim-size tires such as 620/70R46 and 650/85R38 have the same rolling circumference, which is group 48. Use correct tire combinations to maximize tractor performance. Tire sizes for 8020 Series Tractors are found in the table on the following page. If you have any questions or need assistance in choosing the correct combination, see your John Deere Dealer. |
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RX15494,00000CE -19-30AUG02-1/1 |