While shopping for tires, you may be offered—or pressured to buy—road-hazard coverage for your new “investment” (as if you’re buying real estate or gold). Some stores, including BJ's, Costco, and Sam’s Club, provide this type of coverage for free, but many charge an extra $40 to $75 to cover a set of four tires.

The protection covers damage to tires due to road hazards during normal driving. In other words, if you get a flat caused by a nail, glass, or other road debris, the company promises to repair or, if necessary, replace the tire. But if you get a flat from accidentally running over a curb or other driver-caused errors, you get bupkis. And these plans never pay for failure from worn tread; that type of problem is poorly covered under the manufacturer’s warranty.

Unless they’re free, these plans aren’t good deals. First, consider that if a nail flattens your tire, a shop will charge only $20 or so to plug and repair it. Just as you can’t predict when or where you’ll have a flat, you can’t predict which tire will get one, so you’ll have to buy the plan for all four. So you’re paying $60 or so to protect yourself against having to pay $20 or so for each tire repair you may never need. Second, flat tires due to nails and other debris are relatively unlikely. As with any type of “protection plan” pushed by big-ticket sellers, what you’re really being offered is insurance that is highly profitable for the seller but provides little benefit to the buyer.

If the roadside assistance element of one of these plans is of value to you, consider joining AAA, which offers various membership benefits in addition to roadside help.