Spare tires are meant to get you out of a jam, not carry you hundreds of miles down the road. Whether you’re using a compact “donut” spare or a full-size spare tire, it’s important to understand that they’re not designed for long-term use. Driving on a spare for too long can lead to serious damage to your vehicle and even put your safety at risk.
If you’ve got a spare tire on your vehicle right now, here’s why it’s crucial to replace it with a proper tire as soon as possible.
The Difference Between a Spare and a Regular Tire
Most compact spare tires, often called donuts, are smaller, lighter, and narrower than standard tires. They’re built to save space and reduce weight, but they do not provide the same performance, grip, or durability. Their limited tread depth and lower speed ratings are only suitable for short-term use—typically no more than 50 miles at speeds under 50 mph.
Full-size spare tires are better, but they may not always match your existing tires in wear or tread pattern. Using a mismatched tire for long periods can still affect your vehicle’s handling and balance.
Handling and Stability Are Reduced
Because spare tires are not designed to perform like normal ones, your vehicle’s handling will feel different. Steering may feel less responsive, and braking distances can increase. On wet or slick roads, this becomes even more dangerous due to reduced traction.
The difference in tire size and grip can also cause your car to pull slightly in one direction or feel unstable during cornering. These changes in performance are a clear sign that the spare isn’t meant for extended use.
Uneven Wear Can Affect Suspension and Drivetrain
When you drive with one tire that’s a different size or tread depth from the others, it throws off the vehicle’s balance. That uneven rotation can put stress on your suspension, wheel bearings, and other components.
In vehicles with all-wheel drive, a mismatched tire can cause even more problems. AWD systems rely on equal tire circumference to work properly. If one tire is significantly different, it can cause premature wear to the drivetrain and trigger warning lights—or even damage internal components.
Spare Tires Are Not Built to Last
Donuts are made with a thinner rubber compound and limited tread. They’re more vulnerable to road hazards like potholes, nails, or sharp debris. Driving too long on a donut increases your chances of a second flat, which could leave you stranded without a backup.
Even full-size spares can have problems if they’ve been sitting unused for years. Rubber degrades over time, and an old spare may have dry rot or internal damage, even if it looks fine on the outside.
ABS and Traction Control May Not Work Properly
Modern vehicles use sensors in each wheel to monitor rotation for features like ABS and traction control. If one tire is smaller or rotating at a different speed, it can confuse the system and disable these safety features.
That means if you’re driving on a spare in poor weather or need to stop quickly, your vehicle’s electronic safety systems might not perform as expected.
What You Should Do After Installing a Spare
The best thing you can do after putting on a spare is to head directly to a tire shop to repair or replace your original tire. Don’t wait days or weeks, especially if you drive long distances or on the highway regularly.
If you’re using a full-size spare that doesn’t match the others, consider replacing it or rotating your tires once the new one is installed so that all four match in wear and size. This helps maintain even handling and prevents damage to driveline components.
Just Automotive – Tire Help You Can Trust in Williamsburg, IA
At Just Automotive in Williamsburg, we’ve seen plenty of drivers who thought their spare would “last just a little longer.” If you’re currently driving on a spare tire or aren’t sure if your tire is safe to repair, come see us. We’ll inspect your tires, check the wear and balance, and get you safely back on the road with the right fit for your vehicle.
Don’t risk long-term damage—let’s fix that flat the right way.