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].
Replace the tires at least every 6 years. If you're not sure, the minimum replacement time that is recommended by the NHTSA is six years regardless of use, with 10 years being the maximum service life for tires. Check your owner's manual for specific recommendations related to your car.s the tires wear, these bars will become flush (level or even) with the tire's tread. At this point, it's time to replace the tires. 3. Check the tread by using the penny test.  Take a penny, and place it upside down with Lincoln facing you in the center of the tread (at the thickest part of the tire).
You can make sure that the tread on your existing tires is safe by checking it at least once a month when you check your tires' air pressure. Start by culling out the riskiest rubber. Look for bald tires by checking whether any of the wear bars are flush with the tread's outer surface. Another way to check whether your vehicle's tires have reached their wear limit is to insert a penny into each groove, Lincoln's head down, as shown below. Replace the tire if the top of Abe's head becomes uncovered by any of the grooves.