Types of Spare Tires
Compact Spare (Donut)
The small, narrow tire in your trunk. It is lighter and takes up less space than a full-size tire, but it is not built for extended use. The tread is thinner, the rubber compound is harder, and the tire is a different size than your regular tires. It is designed to get you to a tire shop and nothing more.
Full-Size Spare
Some trucks, SUVs, and older vehicles carry a full-size spare that matches the other four tires. A full-size spare can be driven at normal speeds for as long as the tread lasts. If your vehicle has one, you are in much better shape when you get a flat.
No Spare (Tire Repair Kit)
Many newer vehicles do not include a spare tire at all. Instead, they come with a tire inflator kit (a can of sealant and a small air compressor). These kits only work on small punctures in the tread area. They will not fix a sidewall blowout, a large puncture, or a tire that has come off the rim. If the kit does not work, you need a tow.
Speed and Distance Limits
Compact spare (donut):
- Maximum speed: 50 mph
- Maximum distance: 50 to 70 miles (some manufacturers allow up to 100 miles)
- Check the label on the spare tire for the specific limit
Full-size spare:
- Normal driving speeds
- No distance limit (as long as the tire has adequate tread and proper inflation)
Tire repair kit (run-flat sealant):
- Maximum speed: typically 50 mph
- Maximum distance: varies by product, usually 50 to 100 miles
- The sealant is temporary. You still need a proper repair or replacement
What Happens If You Drive Too Far on a Compact Spare
Spare tire failure. The thin tread and hard rubber compound of a compact spare are not designed for high mileage. Drive too far and the tread wears through, the rubber overheats, and the tire can blow out. A blowout at highway speed is dangerous.
Differential damage (AWD and 4WD vehicles). This is the expensive one. A compact spare is a different diameter than your regular tires. On AWD and 4WD vehicles, the difference in tire diameter causes the differential and transfer case components to work harder because the wheels are spinning at different speeds. Extended driving on a mismatched spare can overheat and damage these components. Differential or transfer case repair costs $1,000 to $3,000. Some AWD vehicle owner manuals specifically state that the vehicle should be towed, not driven, if a full-size replacement tire is not available.
Uneven tire wear. The height and diameter difference between a compact spare and your regular tires changes the alignment geometry and puts uneven stress on the other three tires. This causes accelerated wear, especially on the tire opposite the spare on the same axle.
Handling and braking. Your car was designed to stop and turn with four matching tires. A compact spare changes the grip balance. Braking distances increase and the car may pull to one side. ABS and stability control systems may not work correctly with a mismatched tire.
What to Do
The spare tire is a temporary fix. Its job is to get you to a tire shop. Not to get you through the week.
- Put on the spare following your owner manual procedure.
- Drive directly to the nearest tire shop. No detours, no highway cruising if you can avoid it.
- Get the damaged tire repaired or replaced.
- If the damaged tire cannot be repaired (sidewall damage, large puncture, worn tread), replace it.
- Put the spare back in the trunk for next time. Check its pressure periodically (recommended every oil change). Spare tires lose air pressure over time, and a flat spare is useless when you need it.
Frequently Asked Questions
How fast can you drive on a spare tire?
A compact spare (donut) should not exceed 50 mph. Full-size spares can be driven at normal highway speeds. The speed limit is printed on the spare tire itself or on a sticker near the spare tire compartment in your trunk. Exceeding the speed limit on a compact spare risks tire failure and loss of vehicle control.
How far can you drive on a donut spare?
Most compact spare tires are rated for 50 to 70 miles. Some manufacturers rate theirs for up to 100 miles. Check the label on the tire or in your owner manual. The spare is designed to get you to a tire shop, not to be driven on for days or weeks.
Can you drive on the highway with a spare tire?
With a full-size spare, yes. With a compact spare (donut), you can drive on the highway if necessary but keep your speed at or below 50 mph and stay in the right lane. Avoid the highway entirely if there is a surface street route to the nearest tire shop. Compact spares are not designed for sustained highway driving.
What happens if you drive too long on a spare tire?
Driving too long on a compact spare wears it out, damages the differential on vehicles with limited-slip or AWD systems, causes uneven wear on your other tires, and can damage the spare itself to the point of blowout. On AWD vehicles, driving on a mismatched spare can damage the transfer case or center differential, which costs $1,000 to $3,000 to repair.