What Is Tire Dry Rot?
Tire dry rot is common on classic cars because they're rarely used. According to an Angie's List poll, only about 40 percent of classic car owners drive their classic or vintage vehicle more than once a month. (Photo by Katie Jacewicz)
If you notice little cracks running spider-like along the sidewalls of the tires and running all the way to the tread, you may be experiencing a common phenomenon that occurs in stagnant cars – tire dry rot.
One of the most common reasons for tire dry rot is improper storage or infrequent use. According to an Angie's List Classic Car member poll, only about 40 percent of classic car owners drive their classic or vintage vehicle more than once each month.
What are signs of tire dry rot?
Rubber and plastic materials naturally degrade over a period of five to six years depending on the climate, temperature and humidity, the use and storage of the vehicle, and the air pressure levels of the tires. Dry rot is indicated by hard and brittle surfaces on the tires. As the oils in the rubber begin to evaporate, the chemical bonds break down, leaving a dry tire behind.
What causes dry rot?
The most common causes of dry rot include low inflation of the tires, storage near excessive heat and a lack of use. Constant exposure to sun can speed up the effects of dry rot upon the tires, so if your car sits for long periods of time in balmy Florida, for example, chances are your tires will deteriorate quicker.
Finally, if your tires were manufactured several years ago, they could be unwrapping, whether they’ve been on your car the whole time or not.
How can I prevent tire dry rot?
If you have to store your vehicle for long periods of time, ideally store it in a climate-controlled garage, keep the tires inflated to the manufacturer’s recommendations, store it with boards under the tires and check the air pressure at least once a month.
Can you repair tire dry rot?
Dry rot can be fixed only in the early stages. Try using a water-based tire product to help seal cracks and avoid products using petrochemicals or silicone. If dry rot is advanced, the only real solution is to replace the tires.
Is it safe to drive rotted tires?
In most cases, tires with dry rot are probably not safe to drive on. Around town, you may have a little time before you need to replace the tires. Once the cracks reach the cords of the tires, the heat of long distance driving will cause the rubber to expand and the tires to actually break apart while driving.
Editor's note: This is an update of a story that was originally published November 7, 2011.