Drive Tires

[TomC]

There are two styles of super singles.  The old fashion types that are the 385/65R-22.5, 425/65R-22.5, and the 445/65R-22.5.  These are the big tires you see on concrete mixers, trash trucks, dump trucks, and sometimes older fuel tankers.  These old tires usually had a maximum service speed of 65-68mph and were big and heavy.  The modern tires like the Michelin X-one, the Bridgestone and Yokohoma equivalent, are sized at 445/50R-22.5 (direct replacement for the 295/75R-22.5 or 275/80R-22.5) and the 455/55R-22.5 (direct replacement for the 11R-22.5).  These are replacements for the forementioned dual tires, and when replaced on a normal 18 wheeler will save about 600lb and get up to 5% better fuel mileage.  The blow out rate and flat rate went down to 15% of normal reported one fleet of trucks (because the super singles are 20ply tires compared to 14ply for most others).  If I were driving cross country in a big rig, I would have the super singles on my truck, and just carry a mounted spare (loose a bit of weight savings, but have the security of the extra tire). 
As far as running them on a bus, the only three buses I would run them on would be a Crown or Gillig tandem axle or the GMC 4501 also with tandems.  Not with single rear axles, or even ones with a tag axle-to chancy at vehicle loss of control.  Good Luck, TomC