I did a quick search of the internet and found that the 390mm Michelin TRX tires
were a performance option on Mustang GT's from 1979 through 1984.
What I heard was that when it came time to buy new tires
a lot of people found it was way cheaper to buy new 15-inch rims and tires
. Those TRX tires were very expensive.
Mid-80's Ferrari 308's came with TRX tires from the factory.
I put a used set of TRX's on my 1979 Turbo Capri when I bought it in 1988. It had some real bad, non-performance tires on it plus the TRX's were original equipment. I couldn't believe the traction they had cornering on rain-soaked pavement. I could take a 270 degree freeway off-ramp at 60 miles per hour just like I did when it was dry.
Sorry about the non-trailer related post but this is close to my heart. I still have the 1979 Capri with a 1984 SVO fuel-injected turbo four in it and the SVO 16-inch wheels on the 4-wheel Lincoln disc brakes