Just bought a Buhler Farm King 72 finish mower in great shape except for one bad tire although all four should be replaced. When inspecting the rims on each tire I noticed some of the rims had no valve stem or zerk. A couple had both a zerk and valve stem. Is this common or should each wheel have a zerk at least? The valve stem there or not means there is a tubeless tire or not? Why are some tires tubeless and some not? Thanks for the info. I am a numnut and appreciate all the schooling I can absorb. Thank u. Also one tire was a 4.10-3.50 4 NHS while the other three tires were 4.10-4 NHS?