DAVE - WOW, THAT's a tough question actually. The answer is "It Depends". On my tire/rim stuff I had a pair of I think Firestone All Traction Field & Road 10 ply 30.5 x 32 R-1 tires I inherited, along with the proper rims, and My replacement inherited them from Me three years later. But then I had stuff like the 16"x38" double bevel rims that I never had more than a half day supply in the ASRS at any one time that I used about 250/day of and a semi trailer only held 96 or 104 of. But I probably had a two-three day supply on trucks scheduled to be unloaded. I actually got to the point I could actually sleep at night knowing I could keep a Million Dollar an HOUR assembly line in parts AND turn Inventory 300-350 times a year. This was way before the term "JIT" was invented and about the same time the automotive industry was making their big suppliers build warehouses across the street from their plants, but My suppliers were all over the country. I needed 16 or 17 semi-truck loads of tires, wheels, & rims DAILY to keep the line running. A semi-truck load of batteries lasted 4-1/2 days until We switched from common carriers to contract carriers with lighter tractors/trailers and they could haul a 5-day supply from either Kansas City, KS(Delco) or Toledo, OH(Prestolite).
Rockford Clutch, Div. of Borg-Warner was another supplier of mine, clutch pressure plates & clutch discs, on the low volume stuff (Hydro drive plates, 686, 786, 886, 1586 stuff I got monthly shipments, on the high volume stuff, 9, 10 & 1486's I'd get a week or two week supply per shipment. Paint mostly came from Moline Paint Mfg, and a little from Valspar, MPM sent their Engineer in weekly to discuss problems, inventory Our paint, and He'd tell Me what to release. 2150 red mostly came in 350 gallon tote tanks, white, semi-gloss black, etc. came in 55 gal. drums, special stuff like 483 yellow, and the special orange & green for the "Carrot Farm" tractors like the one @ RPRU this summer all came in 5 gal. pails.
I had a stamping house in Dubuque, IA and two o-ring suppliers, National Seal in Downey, CA, and a distributor in Indy. Ohhh also owner's manuals from Harvester Press in W. Chicago, IL. And IH Hinsdale made what was called a "Hammer Strap" for the swinging drawbar which I also had to order the steel for them from WIS. Steel in Chicago. Hinsdale stored the steel and ran the parts and shipped monthly. Most of the smaller quantity stuff I let ship every month. I'd do a little expediting if necessary. We had Stock Chasers on the lines to give Us heads-up on parts We were getting low on, and Production Schedulers who would also have Us chase raw materials in that required machining, welding, etc.
There were 13 of Us scheduling suppliers, pretty much divided by commodity, It was a department NOBODY really wanted to be in, as a former co-worker described the job once, "Yes, and for My retirement job I want to be an air traffic controller at O'Hare AP!".
I handled "Interworks" for 3-4 months and really didn't care for it, mostly E.Moline, Canton, Shadyside, OH stamping plant, Memphis, and Indy for castings.
LVL was their own "Desk", one person was responsible for castings, forgings, machined parts, and assemblies with some help from a second person. LVL eventually supplied the complete assembled transfer case for the 2+2's. They were always in short supply, a "Normal Day" was two air charters with T-cases plus a few on trucks. Keep in mind the 2+2's were supposed to be a 16/day deal between the 2-3 models made. But We were scheduling up to forty-two per day for a LONG time.
But along the way I managed to aquire a real nice collection of insulated plastic coffee mugs from most of My suppliers that were NOT dishwasher-proof, get some prints from Engineering upstairs for FARMALL wire harnesses & battery boxes, buy IH caps, jackets, also win awards from the MP&D dept. for service parts fill rate, everything 100% on-time for almost two years. Ohhh, and to keep this On-topic, talked to someone in Inventory Control or Purchasing in LVL to get the name of the Kohler salesman to buy a K241 for Dad's CC. COMPLETE engine for $300 back in Sept., 1981.