I got three ST225/75R-15D1 113 B Maxxis tires in March 2011 from
http://www.discounttiredirect.com/direct/home.do
Cost was $324. including UPS shipping for the three tires.
Their customer service via email was good. At the time of my order, they could not get "E" range tires from Maxxis so I got the "D" range. Can't remember what that means now...I think it means I got 8 ply instead of 10 ply tires.
I also got an answer about the age of the tires I'd be getting. Excerpt from their customer service email reply (it came with a name of the agent and a phone number also):
"Our policy if to not sell tires as "new" if the D.O.T. numbers are older than 3 years old, the government standard is 4 years. Our warehouses are climate controlled, and kept clean enough to eat off the floor. That being said, I would be surprised if these tires were any older than 18 months. If you get them, and they are older than you wish, let me know and I will send replacements. We are on a "burn and earn" refill. When we sell a tire, we replace a tire, to ensure the freshest stock."
The tires were about 15 months from their mfr. date as I recall. I got them mounted/balanced/steel stems at a local service station and put them on the TM myself (with help/tips from this board). I live in a rural area so this was best option vs. hauling the TM 60 miles away to get the work done at a place that sells trailer tires.