woodlandfarms said:
I am still battling all the logistics of cg / tractor width, yada yada.
I have seen a number of times people claim that R-4's provide a wider stance, but when I go to the tractor dealer, they all say R1, dished out wide, is the widest way to go... Of course there is no one who has a measurement in their brochure.
Anyone want to comment on this?
Woodlandfarms,
I disagree with your dealer. Here is a bit of background on tractor tire width adjustments. I don't know your level of experience with tractors and have broken the explanation down assuming you are coming at this fresh.
Picture this, the wheel is made of two parts. The rim and the center section. The rim typically has 4 or 6 loops welded to the inside, offset from the centerline of the rim. The center section bolts to those loops and to a flange on the axle of the tractor. Starting with the rim positioned so the loops are closest to the tractor, you can then bolt the center to the inside edge or the outside edge of the loops thereby adjusting the distance of the rim center line to the axle flange. (Moves the centerline of the rim closer or farther from the tractor. Because the loops are offset, you can also flip the rim around and move the rim 2 step farther away from the tractor. So, that's 4 adjustments by manipulating the rim.
The center section is typically dished like a pie pan. So the part that bolts to the axle is not in the same plane as the part that bolts to the rim. Flipping the center section will move the outside flange either closer to the tractor than the axle flange or farther away. If you balance a pie pan on your fingertips, the rim can be down or up. The change in distance is equal to 2x the dish.
All this manipulation moves the center of the rim in and out about the same amount for all tire types. Because the width of R4's is about 2x the width of R1's, the outside to outside distance of R4's is greater than that of R1's at every adjustment. This makes the R4 equipped tractor wider and more stable than a R1 equipped tractor. The tipping point is the outside edge, which is farther from the center line of the tractor.
Turf tires can be much wider than R4's, but I don't know if turf wheels are set up to be manipulated. (sorry, no turf tire experience).
To tip the tractor over, you have to move the up-hill tire up higher than the CG of the tractor and move the CG of the tractor outside of the down hill tire. With the tires far apart, that takes some doing. With the tires close together, it's a lot easier. Now imagine that each tire weighs about 600 pounds. The farther the tires are apart and the more they weigh, the higher the tire has to go to move the tractor's CG outside of the down hill tire. That's the benefit of filling the tires with a liquid solution. Because the solution is in the tire, it is close to the ground and that also benefits by lowering the CG further. R4's being larger than R1's hold more solution again benefiting stability.
Whew! Sorry I got so wordy, but there is a lot of detail in tractor stability.
Hope this helps more than confuses!
jb
! Jay
