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.
This allows for inflation, wear and manufacturing tolerances. So you do not need to replace all four tires when you have a flat but you do need to replace the tire with a similar size tire if it cannot be repaired. If all the tires are worn it would make sense to replace the entire set so that they are all matched. have had people tell me that if any one tire is more than 3/32 out that all 4 tires need to be replaced. You mentioned 1/2 inch, that seems like a lot of tolerance, so the tires could be through half of their life and we would only have to replace one tire.