Back when I had my 1700 I checked it out pretty well, and this what I found out for them. The fronts should be between 26# and 46#, and the rears should be between 12# and 23#. It depends on what you are doing with them. If you have a lot of weight on them you go for the high numbers, if just the tractor without a fel, or bush hog, or blade or what ever, then go for the lowest numbers. I did that in the 3 years I had mine and it worked out real good.