Where are all the 19.5 inch tires?

I just purchased Gladiator tires recently, went with standard size on rear dules and wider on the front, what a difference with the wider track, much less tracking on the road. Can check them out at www.gladiatortires.com. My tire shop recommended vs the super expensive Michelin which the tread literally fell apart on. He said they most of the time the tires fall apart before you wear them out due to very little driving and the rubber gets hard so why spend 2x as much unless I was going to be driving it full time.