Wheels are measured at the bead, not the outside diameter of the flange. Look om the tire sidewall- - - -it should show something like "8.25-20" or something similar. The "20" in that example is the rim size.
Today's standard shift transmissions are "synchronized", meaning that the speed of the gears is matched with each other during the shifting sequence to prevent gear grinding. The older truck transmissions, up to the late 1940's, were not synchronized, so a driver had to carefully match the speed of the gears while downshifting by doing something called "double clutching"- - - -letting the clutch out in neutral, speeding up the engine RPM, pushing the clutch pedal back in, and trying to slip into the lower gear without clashing teeth. It'd definitely an acquired skill!
Pre-1954 stovebolt engines do not have replaceable connecting rod bearings. A "soft" metal called "Babbit" is bonded to the big end of the connecting rods, and fitted to the size of the crankshaft journals, then shims are added between the connecting rod and the rod cap to establish clearance for the oil to flow between the rod and the crankshaft. That oil is sprayed into dippers bolted onto the bottom of the rods by nozzles attached to the inside of the oil pan. The proper bearing clearance is about the thickness of a strand of hair, and as the bearings wear, thin layers of shim stock are removed to restore the proper clearance. Too tight, and the rod bearing burns for lack of lubrication- - - - -too loose, (like two strands of hair stacked together, and you can hear a little bit of a rattle. Three hairs worth of clearance, and the rods begins to knock. The more a vehicle gets driven, especially at highway speeds, the more frequently you'll need to adjust the clearance. It's a pretty good system, but it's also somewhat labor-intensive to keep the clearances right!
Jerry
