I'm confused still.   Perhaps I do not understand how the limited slip works.  I thought the front axle was driven by a driveshaft from the transmission which is either engaged or disengaged, like most 4wd pickups.  In order for there to be a limited slip in this driveline, it would have to have a differential in it, like the old full time 4wd pickups which had one diff in the front axle, one in the rear axle, and a third to split power between the two.  I don't think this is how they are and I don't really think this is what you are saying.  The only place I thought the tractor had a limited slip is between the left and right wheels on the front axle....as long as both front wheels are turning the same speed there is no slip so the limited slip and spider gears are doing nothing, the whole differential is rotating as one piece.  Changing front tire size isn't going to make any difference here....tall front tires will make the axle work just like it would if the rear tires had no traction and were slipping, leaving all the power for the front.    This will overload the entire front drivetrain but shouldn't make two hoots worth of difference to the limited slip.