We checked the pressure and nitrogen purity of the spare tire in a Volvo, which as we stated last week uses nitrogen filled tires. The purity was 93.8%, which I believe is above their specification purity of 93.5%. More astonishing was the tire pressure, it measured 54 psig, in a 60 psig tire. It had lost only 10% of its inflation pressure in 2 years of service with no maintenance whatsoever. It was obvious that the spare tire had never been removed or serviced (had to be removed to top off or fill), so this terrific result was solely due to the factory nitrogen tire inflation.
We decided to compare that to air filled spare tires on other vehicles in our employee parking lot. Surveying vehicles in the same time frame, we saw that these tires were underinflated anywhere from 30% to 60%+. Some of these tires were so underinflated that they would be unsafe, if not outright dangerous, to use. By maintaining the usability of the spare, nitrogen tire filling provides a significant benefit to the Volvo driver.
Remember, when you get you get your tires filled with nitrogen, demand that they fill the spare tire as well. Your family's safety could depend on it.