4. Routine maintenance, inspection and operational testing of the emergency generator and associated. components must be overseen by a properly trained person [see MSFC(07), Sec. 604.5; NFPA. 99(99), Sec. 3-4.4.1.1(b)3; NFPA 110(99), Sec. 6-4.7; NFPA 110(02), Sec. 8.4.7].
If rain and wet roads are a concern, you should consider replacing your tires when they reach approximately 4/32 of remaining tread depth. Since water can't be compressed, you need enough tread depth to allow it to escape through the tire's grooves.f two of your tires have a lot of remaining tread depth, but you need to replace the other two because they were damaged or have worn out, you should replace them with a pair of tires that come as close as possible to matching your existing tires.
The bearings themselves are not serviceable so you must replace the whole hub assembly when they wear out. You can check to see if replacement is needed by jacking up the wheels and grabbing the tyre at 12 and 6 o'clock and push with one while pulling with the other hand back and forth feeling for play.