I have the R4's on a Kubota 3540 with weights (no Rimguard dealer around! but that's another story).
I have to agree with the other posters that the decision on what tire to get is very dependent on where you live and what you are doing with it. If you look at some of the posts of people who do/don't like their particular tires, it is often due to a mismatch in needs/tire design.
I use my tractor 1/3 bushhogging fields, 1/3 snow plowing, and 1/3 FEL and other work. The R4's are fine for the field work and the FEL and grapple work, even in the woods. The big issue is snow: if you have relatively light/dry snow, on flat ground, they are just fine. However, if the snow is frozen at all, especially near the base, and you have any hills at all -- even very small ones -- the R4's tend to spin and slide. I've been stuck many times on the smallest hill because of this.
If you have a lot of plowing to do in these kind of conditions, I would recommend chains. I don't have them yet but swear each year I'm going to get them, they just seem to be such a hassle to put on.
Lawns: we have a 'yard' not a manicured lawn, and the soil is very thin. You have to be very careful with the R4's, especially in 4WD. I wait until the ground is very dry before running the R4's over it, and turn very carefully. At least with our lawn conditions, there is no way that I could mow with them. However, it the horse pasture it is not a problem since a few ruts there are not an issue.
My neighbor has turf tires on the same tractor. He uses it mostly to mow and likes them. For snow, he can basically just plow light snow and not on hills.