Maybe you've heard of flat-spotting but you're not sure if it's something you should worry about, or perhaps you're already worried but don't know what to do to protect your tires. Deciding how to respond requires an understanding of the problem.
Flat-spotting occurs when the weight of a car presses down on the same section of immobile tire for long enough, and under the right conditions, to change the tire's circumference from circular to … less circular. Which is not good.. It's more of a problem in cold weather, when rubber gets less pliable, and it's more likely to affect low-profile tires and those with high-performance (cold-sensitive) compounds.
An out-of-round tire causes vibration, which you may have noticed the last time your car was parked overnight in cold weather; if you're lucky, it went away once the tires warmed up after a few miles of driving.
While short-term flat spots can indeed work themselves out, tires can develop a memory and won't return to shape. Scared yet? A little fear is healthy, unless you don't mind spending on a new set of tires after your car sits for a few months over the winter. Assuming you do mind, here's how to prepare for and practice safe rubber storage.
All tires should be stored clean. You might not see it, but dirt and brake dust on the surface can mess with the compound at a molecular level. A soapy bath and a good brush will get the rubber nice and clean.
Even if you take none of the anti-flat-spot precautions detailed below, be sure to fill the tires to their correct pressures before storage. Check them periodically over the winter, since pressure drops with temperature.
Keep the tires out of direct sunlight to avoid damage. If your garage has windows, consider covering them. And yes, this applies to people who live in gray-winter states like Michigan—UV is still out there.
How you ward off flat spots depends on what kind of tires you have, the space you have to store them and your car, and how much effort you feel like putting forward.
If you want to be extra-careful, remove the wheels and tires and store them in a temperature-controlled area—basements are great. This is an extra step for most tires, but it's crucial for R-compound rubber, which is extremely sensitive to temperature change. The wheelless car can either be set back down on a dedicated set of storage wheels and tires—a.k.a. junk you find on Craigslist that fits—or you can put it up on jack stands for motionless safekeeping.
Jack stands also work if you don't feel like removing the wheels or don't need to because you live somewhere temperate or have a heated garage. With stands, there's no load on the tires, so no fear of flat-spotting. Be sure to place the stands securely under a solid mounting point, and use good judgement while lifting the vehicle.
READ MORE: The case for winter tires
If you're not into jack stands or want to be able to move the car during storage, lots of companies make pads that distribute the load around a larger patch, and dollies that allow the vehicle to be moved. Some swear by them, others at them. We use the dollies in the office garage to move vehicles around, and we like them—your mileage may vary.
And if none of that sounds like your cup of tea, you can just move the car occasionally, provided you have the room. Roll the car back or forth every couple of weeks so it's not sitting on the same patch all the time. It's better than nothing.