The high floatation tires were available on any of the number series lo-boy tractors, regardless of year. Narrow turf tires and ag tires were also available. I've seen production/marketing photos of a VERY early 1968 154, with wide turf tires, and a hand-lift for the implements, instead of hydraulic lift. I've never seen one of the number series tractors in person with a hand lift. So, regardless, those wide turf tires were available right at the beginning of the line.
Cub Cadets 682, 1811, 1864, Simplicity Legacy XL 4x4 Diesel with FEL, 60" mower, 50" Tiller