To be honest, I was not going to chime in on this one, but as I too am suffering from old. hard rubber, 13 year old BFG's on my Mach, I decided to add my 2 cents worth.
Just to be clear I only got this car on my doorstep Nov last year -- so I'm still finding **** out
I have learned that my Mickey's could be more than 6 years old - so your clue to poor rubber aging could have some baring
-- I found receipt for tires in scraps of paperwork with the car when I bought him dated 11th Oct 2013 :-/ OMFG !
I also read that the producers of Mickey's specialized in truck tires :-/
Mickey Thompson was into all sorts of racing back in the day - drag racing, Off-Road racing, Indy cars, land speed record, etc. I don't recall which came first, but they produce not only off road ties, but racing tires as well. The Sportsman series fat drag tires have been around since the '60s, as well as the Baja Belted series off road tires. Their street tires are a fairly new thing, only the last 15-20 years or so.
All tires have a shelf life because of the rubber compounds and vulcanizing process - they go bad with time. It's not so much of a problem if you're talking about having some tires on show cars or occasional low-medium speed driving (cruising), but when you need to run at speed and for periods of time, safety is an issue with older tires.
For instance, I have a 1980 Jeep with some Super Swampers on it I bought back in 1996 - and didn't know anything about tire shelf life back then. I have no idea how old they are. But, they still hold air, are still round, have 80 percent of their tread, and show no signs of dry-rot or cracking... so, I still drive it occasionally to car shows, cruise-ins, etc., but not on the highway. When they go they go, then I'll get some more.
Conversely, I put a set of Arizonian Silvers on my wife's '01 Grand Prix (Discount Tire 'house' brand), and she hardly ever drove the car... maybe 55K miles in the 15 years she owned it, and they showed dry-rot cracking between the treads after only 6 years on the car. How's that for not getting your money's worth?
Good luck in your search - I hope you find a set of tires that works out for you.