An increasingly popular alternative to spares is the so-called run-flat design, which most new BMW models use. Intended to make roadside tire changes unnecessary, this solution employs a reinforced tire sidewall that typically lets the driver continue for 50 miles at up to 50 miles an hour after air pressure is lost. But they can be more costly: It may be necessary to replace, rather than simply patch, a damaged tire, and replacements are typically priced $25 to $50 higher than a conventional design.
Another alternative is the self-sealing tire, an older solution reappearing in modern form on the battery-powered Chevrolet Bolt, where reduced weight translates to more miles per charge. Designed solely as an electric vehicle, the Bolt has no provision for carrying a spare. According to Michelin, which supplies the Bolt’s Energy Saver A/S Selfseal rubber, the extra cost of a self-sealing tire — which can continue down the road even with a nail in the tread — is about $33 compared with conventional tires of the same size.
But some models are losing the spare without the benefit of run-flat or self-sealing rubber, instead including conventional tires and a leak repair kit — packaged in an aerosol can or used in conjunction with a small air compressor powered by the car’s battery.
Such kits skim weight while skipping the tire, but have limited abilities to deal with any road hazard more serious than a nail hole in the tire’s tread section. A larger tear in the tire — something that can happen when modern low-profile tires meet a pothole — or damage to the sidewall or wheel rim will not be fixed by a leak kit. The sealants, which are usually one-time use devices, have a finite shelf life — usually from four to eight years, AAA said — and cost about $40 to replace.
Even if a leak sealant kit gets you back on the road in a hurry after a minor puncture, it could complicate a permanent repair. Affixing an internal patch after a sealant has been used requires a thorough cleanup of all the goo inside, said Tom Carter, technical communications director for Michelin.
For a car owner — and certainly renters who might not know what they are getting into — the best way to prevent an unpleasant middle-of-the-night surprise is to check for a spare and be sure that it holds air. If there’s a sealant kit instead, read the owner’s manual (which may be on a DVD or available on the car’s display screen) and learn how to use it.
In some cases, greater peace of mind is available from the automakers.
For instance, although mainstream versions of the 2017 Honda Civic come from the factory with space-saver spares, the Civic Si does not. A spare wheel kit, including a jack and tools, is available from Honda dealers as an accessory for the Civic Si at a suggested retail price of $254. The tire, which must be purchased separately, runs about $115 from sources like Tirerack.com.
BMW offers a compact spare kit — including jack and wrench — for many of its X Series sport utility vehicles and for the 5 and 7 Series sedans. In most cases, it’s a $150 option when ordering the car, though on some models with conventional tires it is free. On the sport utility models, the compact spare fits entirely within a compartment under the rear floor, but on the sedans it juts out too high, meaning the floor panel cannot lie flat.
Not surprisingly, independent online retailers have also emerged to fill the hole. Buyers should make sure to compare prices with the dealership and to determine that there is a storage spot in the car where the tire can be secured. As designers work to smooth airflow under the car for fuel-economy improvements, those compartments are going away, too.
The disappearance of the spare tire might be more than just an exercise in efficiency. It may be a sociological statement. A survey by AAA found that some 20 percent of drivers do not know how to change a flat tire, and with the rise of roadside assistance coverage for new cars, that number is unlikely to shrink.
The era of cars proudly displaying a spare tire mounted on the front fender or rear bumper — a standby of prewar classics — is long gone, and the tradition of suburban dads gathering to inspect a neighbor’s new purchase may have to undergo a major change.
Instead of crowding around the front end to see what’s under the hood, perhaps they’ll be checking the trunk to see if it’s got a spare.