These are very helpful when determining the real width and diameter of the installed tire, espeically if you are upgrading to a new wheel size. After you pay for the special order and install them on your wheels, it is too late to return them. Ask the representative tire retailer how you can interpret the data codes. If they do not know how to or show no interest in helping, go somewhere else. Lastly, the haunting thing that Yokohama's Georgre Lugo reminded us of is that a brand new high performance tire that has been stored too long will never perform well and may be unsafe.
Tires are life limited as the rubber ages and deteriorates with time.
My good friend with the RUF car had a 930 with tires that looked new, but were over nine years old. One afternoon while acceleratirng past 60 mph on I-10, the left rear tire exploded. The driver thought the car would flip as he fought to control it. When he got off the freeway, he found the tire in shreads. He eventually discovered all four tires were weather cracked through the sidewall and showed signs of tread separation.