When were the rubber boots (solid legs)used instead of the glides (for hollow legs)used on the lcm's?

I found this history of the boots from a description from the Eames Collector Website. Which is run by Steven Cabella and is a highly recommended resource.

"The earliest of the Eames plywood production chairs had few feet design issues and presented no real problem in this regard, in fact the small feet on the LCW and DCW acted as the protector of the plywood leg ends in several ways. Perched on four small metal tack heads, the tack heads facilitated sliding the chair on the floor and also act to elevate the chair just enough to protect the plys of the wood legs from chipping off when dragged on some rougher flooring surfaces.

The early metal framed plywood chairs presented the major recognition that a chair tip was an honest visual part of the function of the chair and of concern to the consumer. The first tip was a simple gray solid rubber washer attached to the bottom of the metal leg with a washer and machine screw, in fact, like several of the early connecting parts and metal tubing parts of the Eames tables and chairs, this gray rubber bumper was borrowed from the pluming parts industry. The ability of this simple rubber tip to be torn off while sliding the chair, necessitated redesigning the chair tip for better functionality, the reevaluation being a common step in the overall design process at the Eames Office. The result was the use of the black rubber and stainless steel "Domes of Silence", a push on model of a smooth sliding chair tip or glide, acting like a more developed version of the tack head used on the all wood chair. It was a new glide with the look and materials exactly matching those used in the rest of the chair frame. A small, slightly rounded stainless steel tip designed to glide silently over most flooring surfaces, thereby doing away with noisy chairs sliding in schools, offices and lecture halls. A very small detail, but of equal importance to the design process at the Eames Office.

These new slide-on boot tips were again replaced in the early 50s with another improved one. This time the design answer was to permanently attach the glide to the chair leg, first with a shorter glide that was force fitted on with a knurled stud, when this made the replacement off broken feet impossible for the consumer, they again redesigned the glide to screw in and out for easier replacement by the owner. These same tips, but larger, were used on most every piece of Eames designed furniture including Cabinets, the 671 Lounge Chair with ottoman and the Stephens Speaker cabinets. Once the Eames Office designed their new fiberglass chairs and the variety of new chair bases that evolved with it, the issue of glides or tips was confronted again. The 1950 wood dowel legged chair was the last Eames chair with wood elements almost touching the floor. Learning from the rusting and staining of the metal tacks used earlier on the wooden chairs, the Eames office chose to use a clear round plastic tipped foot. Made at a local factory in Santa Monica, near the Eames Office, The tips were made of a small nail with a pattered nail head cast into a clear acrylic button. This not only solved the rust issue but had the added visual benefit of making the foot element of the chairs design almost visually disappear.

The other new bases were all made of metal tubing or resistance welded wire rods and presented another evolution in chair tip design at the Eames Office. The first production tip for the new "Eiffel Tower" wire bases was a "Dome of Silence" glide that bolted though a hole in the bent leg end that formed a foot for the bolt. This glide was followed a few years later with a black rubber and steel foot that pushed-on the ball end of the rod legs, this tip was self leveling for more comfort on slightly uneven surfaces. And again in the mid fifties, this model glide, on the wire bases, was replaced by the all new and all white nylon self-leveling glide.

In 1955, the replacement of the first issue heavy solid metal tubing x-bases that used the "Domes of Silence" with the new H-bases made from hollow steel tubing meant that new feet were needed again. The first foot tried was the same first issue slide on boot glide but with a small plastic tip inserted into the tubing end to provide better footing for the boot glide. The next year new black rubber and steel self leveling tips, resembling the early Eiffel Tower self-leveling tip, were designed to be inserted into the hollow tube end of the new steel h-base legs. This was followed by another design change the next year the use of long lasting and non rusting white plastic nylon for a newly designed self foot that provided the final answer for the h-base foot connection"