1)- It lowers the tractor to make it more stable*.
2)- It widens the rear track to make it more stable
3)- The tires are rated at around 4 times the weight capacity of the factory tires. Many factory tires are rated at as little as 350 pounds! If you have a loader and keep blowing out tires you can really appreciate this.
4)- The replacement tires for this kit are much cheaper. A single rear factory tire can be over $300ea!
5)- The wider tires increase the tractors footprint causing much less soil compaction- Better for your yard.
6)- The less aggressive tread pattern will not disrupt your yard but still gets BETTER traction in many conditions **.
7)- Your neighbors will be totally jealous because it just looks cool!
Check it out here--
http://www.hoyetractor.com/turf.htm
*- some of the very small tractors like the YM1100, 1300, etc will see about a 0.75" increase in ride height. This was due to the already low stance on these tractors.
**- The tread is a mix of turf & industrial that gets very good grip. Believe it or not, these tires actually have better grip than the lug tires in most conditions! Unless you have around 2" of soft or muddy soil you will get better grip with these tires due to the increased surface area. If you think about it, on the lug tires or the "rice" style tires you are only touching the tips of a few lugs on normal ground. Even in muddy or very soft conditions these turf / industrial tread style tires do very well because of the width & deep tread.