Tire Dry Rot: What It Is, Why It Happens, and How to Stop It – Jalopnik

Unlike organic fungus that eats wood and organic materials, tire dry rot is a chemical breakdown that manifests as cracks, discoloration and fissures in a tire’s sidewalls and tread. Fresh tires are flexible and have a deep black tint. But with time, extremely hot or cold weather, UV exposure, inactivity and inadequate storage methods, dry rot or cracking in the side walls is inevitable.

More specifically, dry rot occurs in older tires, especially those that are between six and ten years older than the date of manufacture, a period that most tire manufacturers consider to be too old for safe driving. Although tire manufacturers assume that consumers will most likely use a set of new tires well before their six- to 10-year expiration date, knowing the tires’ production date or DOT date code before purchase is cheap insurance against dry rot. And that’s because, yes, tires can expire or deteriorate before they wear out.

In some cases, dry rot begins as small, almost unnoticeable cracks in the rubber surface. At this point, the tire may still hold air, but these cracks can grow larger and spread to more parts of the tire if neglected. When this happens, the cracks can spread significantly on the outside and inside and become so large that the steel belts begin to break apart and the tire loses air. In the worst case, a blowout occurs where the tire disintegrates while driving.

In that regard, tires with cracks in the sidewall are unsafe to use. Edmunds reports that 250 incidents of loss of control and rollover accidents in 2012 were caused by vehicles with tires older than six years, all of which had visible separations between the belts and the tread. Since tires are your car’s only points of contact with the road, it is unwise to hedge your bet on dry-rot tires, even if the production date is less than the six-year threshold, or regardless of the remaining tread depth.

In reality, you never have to think about your daily driver’s tires dry rotting as you will most likely replace them before they start to go bad. More worrying is the long-term storage of tires, as improper handling will certainly lead to wood rot and permanent damage. The trick is to clean the tires before storing them, pack them individually in airtight bags, and carefully stack them in a cool, dry place in your home or garage.

And if you notice that your tire’s sidewall and tread are slowly cracking or that some parts of the tire are starting to fade or discolor, these are some of the signs that you need new tires, including balding treads and noticeable bulges on the tire. Finally, make it a habit to rotate tires every 3,000 miles and visually inspect them for bulges, cracks, or uneven wear.