The Ultra CRT are ST tires and are made by Carlisle. I too had one blow on the way home on I95. I could not find a replacement within 100 miles North. I found a piece of metal in my sidewall that I attributed to the blowout. I ended up buying a LT tire and putting it on as a spare. go to
http://trailertire.com and you can find them - here is the size info you need: I am not happy that these tires are not readily available when traveling!
STOCK #: 1604126
Load Range: E (10-ply)
Max. Capacity (Single): 3640 lbs. each
Max. Capacity (Dual): 3200 lbs. each
Overall Diameter: 31.7"
Maximum PSI: 80 lbs.
CARLISLE'S 'RADIAL TRAIL' Series Trailer Tire
Price: $136.95