Welcome to the site!
This has been beat to death on every site that has anything to do with flying in the sticks, but since that was your first post maybe you just haven't noticed.
Since like most of us your are probably flying for the fun of it, just analyze where you fly and buy the tire that will do the
most for
you. Buying the smallest tire you can get by with will be buying the tire that will do the least for you, unless your goal is speed. In which case you failed by not buying a Lancair....
The goal in an off field tire is decreased rolling resistance coupled with increased shock absorption... plain and simple
The idea that bigger tires will hurt your airframes is fundamentally flawed. The loading that will damage your airframe is not sustained load, but shock loading. At that instant, the tire is in compression (a lot in a Bwheel) not only shrinking that "arm" but also dampening the shock. One landing on rip rap size gravel in an all metal plane with and without B wheels will teach you this..Two landings will have you getting out of the non equipped plane... or fixing it.
Wup will correct me if I am wrong here, but I believe the sidewall is much stiffer in the 29" vs the 31" B wheels. In a plane as light as yours this is not good...I would think towards either 26" B wheels or 31" B wheels.
If Your flying takes you into the sticks regularly. Notice I said the sticks and not "back country airstrips" Which for the purpose of this conversation could be called a dirt, gravel, or grass airstrip...
If you will be more of a sunday morning to the local dirt strips type (and there is nothing wrong with that) then 8.50s will be all you will need and more. They will also keep your pocket book happier.
Does anyone know what exactly happened to the guy who landed the maule in the sand and got stuck? I don't... but I do know he borrowed a set of Bwheels to get out...Ironically when I briefly spoke to him after that event he said he still wasn't sold on Bwheels...
Take care, Rob