(ET) Tire chains source?

[<Joel Parks nokia com>]

So I had the opportunity to try out the E15HA+Alltrax + snowblower on a 
couple inches of snow this morning.

I forgot to slip in the counterweight box and find some bricks in the yard 
to fill it with - but I think even if I'd done so, I'd have some problems 
on some slopes.

So I'm in the market for chains.  

Does anyone have any particular tips or advice regarding acquiring or 
using chains?

Does anyone have a favorite source for tire chains for "23x9.50-12" tires?

thanks,
Joel