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).
The answer to this question really depends on your car. Most of the cars on the road today are front-wheel-drive, and a few are rear-wheel drive. These don't necessarily need to have all four tires replaced at once.Usually two at a time is sufficient.But all-wheel-drive systems are becoming more popular, and they do require all four tires to be replaced at one time. So for AWD vehicles, the short answer is yes, but let's find out why.hese don't necessarily need to have all four tires replaced at once. Usually two at a time is sufficient. But all-wheel-drive systems are becoming more popular, and they do require all four tires to be replaced at one time.