Why Your Spare Tire Could Fail You on a Summer Road Trip
Summer road trips send millions of Americans onto interstates each year, and tire trouble remains one of the most common roadside problems handled by AAA. The overlooked issue is the spare tire, which tire makers including Michelin, Goodyear, and Bridgestone say can age out or lose pressure long before drivers need it.
What the industry is warning about
AAA said in prior roadside safety guidance that many drivers do not inspect a spare during routine maintenance, even though it may sit unused for 5 to 10 years. That matters because compact spares, often called donuts, are built for temporary use and usually carry limits of about 50 miles and 50 mph, based on labeling commonly used by major tire brands.
Michelin states that even a never-used tire ages over time, and the company recommends annual inspections starting at 5 years, with replacement no later than 10 years after the date of manufacture. Goodyear and Bridgestone publish similar maintenance guidance, and both companies say proper inflation is critical before any emergency use.
The National Highway Traffic Safety Administration has also warned drivers to check the spare tire as part of basic vehicle readiness. On a hot July trip, a compact spare that has been sitting under a trunk floor since 2016 or 2018 may be well past the point where a shop would consider it road-ready.
What drivers are seeing on summer trips
The risk is national, but it becomes more relevant on long summer drives through hot-weather states such as Texas, Arizona, and Florida, where pavement temperatures can climb well above air temperature. Heat raises stress on rubber and air pressure, and the Rubber Manufacturers Association has long said that underinflation is a major factor in tire failures.
What is confirmed is that many spare tires receive little attention between vehicle inspections, oil changes, or battery replacements. What is not known is exactly how many cars on U.S. roads currently carry an aged or underinflated spare, because automakers and tire companies have not released a nationwide count.
For drivers, the practical limit is simple. A spare may get a car to the next exit or service shop, but it may not be safe for a 200-mile push to the beach or mountains. Owners’ manuals from brands such as Honda, Toyota, and Ford commonly direct drivers to replace a temporary spare with a full repair as soon as possible.
Why spares fail and what it means now
The main causes are age, low air pressure, and misuse, according to guidance published by NHTSA and major tire manufacturers. A compact spare can lose pressure while hidden in a trunk or under an SUV, and some temporary spares require inflation pressures near 60 psi, far above the roughly 32 to 35 psi many drivers expect in regular tires.
There is also a design issue. Many newer vehicles sold in the U.S. over the last decade came with tire repair kits instead of full-size spares, largely to save weight and fuel, a change documented across model lineups from brands including BMW and Nissan. When a vehicle does have a spare, it is often smaller and less durable than the original equipment tires.
For travelers this summer, the takeaway is practical, not dramatic. The spare tire should be treated like any other tire with a date code, pressure specification, and service life, and automaker guidance still treats it as temporary equipment. That means an old donut in the trunk may not be a reliable backup in July 2026, even if it has never touched the road.
