Old tires might not be as dangerous as you think—if you store them correctly
Of all the parts of your car that deteriorate from literally existing, tires are the most talked about. Ask a dozen folks at your cars-and-coffee group about tire age and you’ll somehow get 14 differing opinions about how seriously to take the aging of the rubber that connects your car to the road. It’s a legit safety concern, but generally the discussion will boil down to someone citing “something they heard from a friend a while back.” Luckily, Ari Henning took a deeper dive into answering the question—and he even put his body on the line to find out.
This video was distinctly aimed at motorcycles, but there is a point at which tires are tires, and all our vintage cars have tires that get used about as much as most motorcycles. That means we should really look at this research and study it to glean a bit about our rubber too, and there’s plenty to learn.
The most common thought—and even I am guilty of this—is that tires should be replaced after five years even if they still have tread and appear serviceable. Ari asks the hard question, though: Is that a myth put out by the tire manufacturers to sell more tires, or simply a misunderstanding?
To resolve the first part of that question, he called some tire manufacturers and asked. The short answer is that it’s not that simple. Tires do age, but because that aging is due to a myriad of factors and is a safety concern, tire replacement guidelines rightfully fall on the conservative side. Five years, however, is a little too conservative. Only one producer, Avon, recommended anything close: seven years. Other brands—Bridgestone, Michelin, Dunlop, and Continental—agree that 10 years is the maximum lifespan for a properly maintained set of tires. That seems like a crazy number, but Ari decided to put his money where his motorcycle is. He found a 7-year-old set of Bridgestone RS10 tires, mounted them on the wheels of a GSXR1000 track bike, and put them to the test to see if it they would stick or slide.
Surprisingly, not only did his bike stay upright, but the “ancient” tires had enough grip to keep a pace similar to that of a brand new set. It’s not surprising. Why? Mainly because those old tires were stored properly. Here are some storage tips not just for motorcycle tires, but for your car’s tires as well.
Keep your cool
Tires should be kept in a cool place. Heat makes the oil in the rubber compound rise out, and thus makes them turn rock hard faster.
Oxidation is the enemy
Oxygen is necessary for life, but it also can kill a lot of things we hold dear—tires included. The elastomer molecules in tire rubber compounds get harder and weaker when exposed to oxygen. Sadly, there’s not a lot we can do here short of putting our tires in a nitrogen-filled bubble.
Hello darkness, my old friend …
Ultraviolet exposure also serves to degrade tires, and thus the best storage solutions are out of the sun. If necessary, resort to a black trash bag. There’s a reason you see long-parked RVs or trailers with tire covers. It really does help.
Say O-no to Ozone
A byproduct of combustion or oxygen being exposed to electrical current, ozone is the leading cause of dry rot in tires. That means storing tires in your workshop might be the worst place, compared to a crawlspace or basement (assuming there are no appliances in that basement.)
Don’t stress it
Mechanical stress is just a fancy way of saying carcass flex. It’s unavoidable when a tire is mounted and in use, but when storing a tire—like your winter tires or a spare set—it is best to not stack them, as that puts additional stress on the one at the bottom.
There is nothing you can do to completely halt a tire from aging, but with a little careful attention you can maximize the life of your tires and get the full long life they deserve. After all, it is a good bit longer than any of us thought.