12" tires on a 10" rim has been working for years now. It is a good combo. I highly recommend it. The problem with the narrower rim is the sidewall rollover on highway use. Makes it feel squirlley.
Thanks Cruzila!
I guess the regular TSL's are also an option. How do the TSL's compare to the TSL/SX? The SX is a tougher tire with some sidewall tread.