Most Common Spare Tire Problems (And How to Prevent Them)

Marko S.
Dec 3
3 min read

Your spare tire is your backup plan — but only if it’s in good condition when you need it. Many drivers don’t realize their spare could already be unsafe, flat, or damaged long before it ever touches the road. Because spares sit unused for years at a time, they often face problems that regular tires don’t.

Here are the most common spare tire problems and how to prevent them from becoming dangerous.

Dry Rot (Cracking Rubber)

Dry rot is the #1 issue with spare tires, especially rear-mounted spares.

Causes include:

Sun exposure
Heat
Oxygen breakdown
Weather cycles
Age

Signs of dry rot:

Cracks in the sidewall
Chalky or gray rubber
Hard, brittle texture
Cracks inside tread grooves

Prevention:

Use a UV-blocking spare tire cover
Inspect the spare every few months
Replace after 6–10 years based on date code

A simple cover dramatically slows dry rot.

Low Air Pressure

Many spares sit untouched for years and slowly lose air.

Problems caused by low PSI:

Unable to drive on it safely
Risk of rim damage
Faster tread wear when used
Possible blowout

Prevention:

Check air pressure every 2–3 months
Inflate to the pressure listed on the tire or door sticker
Inspect valve stem for leaks

Donut spares need especially high PSI — they lose pressure faster.

Expired Tire Age

Even unused tires expire.

Tires older than:

6 years → Inspect carefully
10 years → Replace immediately

Old tires can look “new” but still be unsafe.

Prevention:

Check the DOT date code on the sidewall
Replace aged spares before they fail

Aged rubber can’t be restored.

UV Damage and Fading

UV rays break down rubber and cause cracking, fading, and loss of strength.

This is a huge issue for rear-mounted spare tires.

Signs of UV damage:

Faded color
Surface cracking
Dry surface texture
Stiff rubber

Prevention:

Use a high-quality vinyl spare tire cover
Park in shade when possible

A SpareCover® blocks UV rays and slows rubber breakdown significantly.

Moisture and Weather Damage

Rain, snow, humidity, and ice all damage exposed spares.

Problems include:

Water trapped around the bead
Accelerated aging
Rubber weakening
Corrosion on the wheel
Rust on mounting hardware

Prevention:

Use a waterproof cover
Rinse off winter salt
Clean the tire and wheel occasionally

Marine-grade vinyl protects against year-round weather.

Debris Impact (Stones, Gravel, and Dirt)

Exposed spares get hit constantly by:

Gravel
Sand
Stick debris
Mud
Dust
Road oil

This causes abrasions and long-term wear.

Prevention:

Use a durable vinyl cover
Clean off dirt buildup occasionally

A cover acts like a shield for the tire.

Loose or Damaged Mounting Hardware

If the spare isn’t mounted securely, it may:

Rattle
Wear unevenly
Loosen over time
Become dangerous on the road

Signs of mounting issues:

Wobbling
Clunking sounds
Visible rust
Loose bolts

Prevention:

Check the mount once or twice per year
Remove rust from hardware
Ensure bolts are tight
Replace worn brackets

Donut Spare Limitations

Temporary spares have their own problems:

Lower speed limits
Short distance limitations
Narrow tread
Faster aging
Higher air pressure needs

Prevention:

Check donut PSI more frequently
Replace older donuts earlier
Use only for short trips to a repair shop

Donut spares should be treated as true temporary solutions.

Incorrect Spare Tire Size

Some used vehicles come with mismatched or incorrect spares.

A wrong-size spare can:

Damage the drivetrain
Throw off traction systems
Make handling unsafe
Strain suspension components

Prevention:

Match size to the factory recommended tire
Confirm load rating and sidewall height
Replace mismatched spares immediately

Final Thoughts: Prevent Spare Tire Problems Before You Need It

Most spare tire problems come from one thing: neglect.

A spare sits quietly for years, slowly aging, losing air, and taking damage from sun and weather. By the time you need it, the tire may already be unsafe.

The easiest way to prevent these problems is to: