Derek,
If you feel you need for "full time weight" then by all means go for the filled tires, it is your best option. Another option is wheel weights. At least you can take them off if you are finding you are ripping up your turf.
I run R4's and I have to tip toe through my lawn (but I am much heavier then you are), Ag's will really do a number on your grass, even with your BX.
It is all a trade off. I like the option of being able to remove the weight if possible.
Good luck,
Gary