Kelly has nailed those tires exactly, as I would presume an old-time dirt-runner would know! Those diamond-pattern tires were initially produced by Firestone, very early in the history of earthmovers conversion to rubber.
R.G. LeTourneau, like so many earthmovers of the 1920's and early 1930's, used steel wheels on his earthmovers.
However, the earthmoving industry - and LeTourneau in particular - became keenly interested in the possibilities of rubber tires being fitted to earthmovers around 1931.
The benefits were easier road transportation, vastly reduced drawbar pull required to load, greater operating speed, and less impact to axles, bearings and chassis' over rough terrain.
The speed factor was critical - as LeTourneau, with an earthmoving contractor background, was always interested in faster speeds - which led to substantial increases in productivity.
There was also a very noticeable improvement in productivity, due to lower power losses involved in pulling the rubber-tired earthmovers, as compared to steel-wheel models.
LeTourneau started fitting truck tires to his Carryalls for road transportation from job to job. The truck tires were fitted for transport, then removed and replaced by the steel wheels when on the job. The contractors of that era wouldn't even dream of using the scraper to haul dirt while the truck tires were fitted.
However, LeTourneau became enamoured with the idea of using earthmover tires, when he carried out some tests using heavy duty truck tires on his Carryalls, and found that the power required to haul the scraper fitted with rubber tires, was as low as 1/8th that of the units fitted with steel wheels.
The first recorded sale of a new earthmover fitted with rubber tires ex-factory, was to Basich Bros Construction Co of CA, in August 1932. Nick Basich, CEO of Basich Bros, had been given a Carryall by LeTourneau, that was fitted with truck tires, as a free demo - to run it against steel-wheeled Carryalls.
The amazing improvement in the productivity of the Carryall fitted with rubber tires, saw Basich sold on the idea of rubber tires in earthmoving, and the earthmover tire soon gained industry acceptance.
The tires fitted to Basich's Model A Carryall were 12.00 x 30 highway truck tires. These were over-inflated at pressures up to 90 psi, to try and make them carry the excessive loads imposed on them by the Carryalls fully-loaded weight.
Meantimes, LeTourneau had run into a brick wall with the tire companies. Despite his entreaties to them, to get them to build him an earthmover tire of greater capacity and durability than the truck tires he was using - the tire companies weren't interested.
They could see no market for such a tire, they claimed - and they weren't going to waste design and manufacturing money on a tire for which there was no market. The cost of a huge new tire mold was horrendous.
Whilst supplying new Carryalls fitted with the heaviest dual truck tires he could find, LeTourneau still found these proved inadequate for the work, due to insufficient strength. He then turned to large aircraft bomber tires.
LeTourneau managed to purchase as Govt surplus, a large number of heavy duty bomber aircraft tires, built by Goodyear, and known as "Airwheels". The U.S. Govt had ordered all these tires for a bomber program that was scrapped as a result of the Great Depression.
These huge tires were 46.00 x 20 in size - but despite the massive size increase, the bomber tires were still inadequate for earthmover use - because the smooth tread and the lack of reinforcing in the sidewalls (all part of the design for smooth runways), soon saw these tires failing rapidly in the much harsher earthmoving job application.
After constant pressure from Le Tourneau, the Firestone Company provided some experimental earthmover tires that were used on 4 Carryalls that worked on the Cooney Dam project in 1935.
Frustrated with the tire companies lack of interest and progress with earthmover tire production, LeTourneau instructed his engineers to commence the manufacture of a large earthmover tire mold to produce earthmover tires to his design.
The idea was that the very expensive and complex tire mold would be provided by LeTourneau, to the tire companies, so they could make the tires for LeTourneau. The first stage of this major project involved the construction of a special LeTourneau boring machine, which was required to manufacture the tire mold.
When Firestone got wind of this project, they realised they had to treat LeTourneau's repeated earthmover tire requests seriously, and responded with alacrity. They promised LeTourneau they would provide him with his requested earthmover tires - provided he purchased a minimum order of $1M worth of tires!
LeTourneau agreed, and the first of the new Firestone Earthmover tires appeared in 18.00 x 24 size in 1935. This was an improved version of the experimental earthmover tires that had been fitted to the 4 Carryalls at Cooney Dam.
Surprisingly, the tires were still marked, "Truck & Bus" - leading to the perception that the Firestone company still wasn't convinced there was any market for earthmover tires!
These first earthmover tires were heavy duty, high-number-of-plies (usually 16 to 20 ply), diamond-pattern, flat bead tires, that used a heavy-duty tube, and were inflated at pressures up to 70 psi.
These new earthmover tires were completely successful, and allowed LeTourneau to manufacture larger models of Carryalls - and these tires were the forerunner to todays earth mover tires. Goodyear rapidly followed Firestone into the production of earthmover tires.
The turf tires that were produced from around the late 1950's/early 1960's were a slightly different design to the original Firestone & Goodyear earthmovers. They have a lower new tread depth, and evenly-spaced, angled grooves in the tire - as compared to the slightly disconnected grooves in the diamond-pattern earthmover tire.
These turf tires were produced as an answer to the substantially increased number of golf courses and grassed areas of that era, that called for a tractor tire that didn't damage delicate grassed areas.
The turf tire was designed as a tractor tire, but could be fitted to tractor-loader-backhoes. They were not designed for maximum grip, as the original "bar-tread" or "leg-of-mutton" lug tractor tread was. They were designed to give modest amounts of traction without tearing up grassed areas excessively.
Turf tires were never designed for earthmover fit and heavy-duty load capacity - and even the Firestone & Goodyear diamond-pattern earthmover tires were never designed for fitment to powered drive wheel positions, such as the A-C scraper pictured.
The Firestone & Goodyear earthmover tires were always designed for, and used on, trailing and non-powered earthmover wheel applications.
It's quite possible that the A-C 260 scraper uses the original, pre-WW2 20" earthmover rim, which became obsolete in the early 1960's, being replaced by the standard 25" earthmover rim size. As a result, the owner would have been finding it difficult to source the 20" earthmover tires new, and settled on some much cheaper, used 20" Carryall tires.
