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.
However, what is also important is tyre mileage. With an average of around 27,000 miles per year, summer tyres should be replaced at three and a half years and winter tyres after a maximum of seven years (assuming that the tyres have only been used each winter).