There is one main thing to consider here. Making a wider wheel stance on the front axle does not help stability at all. It puts much more strain on the center pin that your axle pivots on. This can, and more probably will cause premature wear on the bearing, and the seals for that bearing, that you axle pivots on.
If you want more stability for your tractor you can add spacers on the rear wheels. That is effective to some degree depending which model tractor you have and how you are using it. Check out the thread on wheel spacers and discover what spacers others are using and if they experienced any problems with them.
My tractor is much smaller than yours and I added 1 3/4" spacers to the rear of mine. I am very happy with the results. Others have added 2" or larger spacers and they are happy with those. You may feel the need for more stability but you will not achieve it by making your front wheel stance wider.
I tried putting 1 3/4 inch spacers on the front of my tractor but I ended up removing them after a few weeks of use. My property is very rocky, but flat. Since my property has a lot of rocks my front axle is often flexed to each side and the front wheels come off the ground frequently. With the spacers on the front, I was experiencing the front wheels coming off the ground more frequently than without the spacers. Since the front wheel that was still in contact with the ground had excess weight on it, more than would be with the narrower wheel stance without the spacer, that caused a fluid seep from the front axle pivot bolt. I was able to cure that by tightening the pivot bolt but I decided to remove the front wheel spacers and that problem never appeared again.
Take what you will from that experience but it is real, not anecdotal.
