This response is on the Bridgestone website. It addresses storage of tires quite well. The one part that it does not fully address is flat spots from sitting for prolonged periods of time. The response does say that flat spots MAY work themselves out, but goes on to say, not always..... I've never raised my ties off the ground for storage on any of my trailers or sports cars that were stored for winter and I've never had any damaged tires, but that certainly doesn't mean it's not a good idea.
Here's the Bridgestone article and website:
Dear Tire Doctor,
Can storing a vehicle on concrete effect the tires? Should I put barriers like plastic or other non-porous material under the tires? How about the effects of continuous storage for several days at a time with use between storage periods?
Thanks for your help on this subject.
Best Regards, Len
Thank you for contacting Bridgestone and allowing us to assist you.
First of all, regarding the effects of storage:
A cool, dry, sealed garage is your best condition for storage, however, it is realized that this is not often an available option. Concrete is not the tire enemy some people think it is.
We would recommend the following steps in storing a vehicle:
1. Make sure the floor / ground surface is free of any petroleum product contamination (Oil, grease, fuel, etc.) since petroleum products will attack rubber and can cause significant damage to compound characteristics.
2. Thoroughly clean your tires with soap and water.
3. Place a barrier such as plastic, cardboard, or plywood between the tires and the ground surface.
4. Cover your tires to block out direct sunlight and ultra violet rays.
5. Do not store the vehicle in close proximity to steam pipes, electrical generators or animal manure since these accelerate oxidation of the rubber.
6. Make sure your tires are fully inflated with air.
7. When the vehicle is ready to go back into service, inspect the tires for excessive cracking in both the sidewall and tread area and check all tire air pressures. Tires will normally lose about 2 PSI per month so you should expect to find the pressures lower than when you put the vehicle into storage. Re-inflate the tires to the correct air pressure before operation.
Now, about the effects of time:
Yes, rubber compound does slowly change over time, becoming "harder" as it ages. But unless we are talking years, this would be virtually undetectable. However; the most likely effect of storage will be:
1. Flat spotting of the tires from taking a 'set' while sitting in one position for an extended length of time. This 'set' may work itself out of the tires after being put back into operation, but not always. This, of course, would result in a vibration.
2. Tires have waxes and oils specially formulated to protect against ozone damage built into their rubber compounds. When the tire rotates and flexes, these waxes and oils are forced to the tire's surface and are thus able to protect the tire. When a tire is stationary, these waxes and oils are not coming to the surface and thus the tire is at greater risk of ozone damage.
3. Several days of non-use at a time is not nearly as detrimental to tires as long storage periods. The tires would still be operated often enough to avoid excessive 'set' and the waxes and oils are being forced to the tire's surface often enough to provide adequate protection against ozone.
Best regards, Tire Doctor