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Signs Your Spare Tire Is Dry-Rotting (And How to Prevent It)

  • Writer: Marko S.
    Marko S.
  • Dec 3
  • 3 min read

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A dry-rotted spare tire is one of the most dangerous situations a driver can face. You expect your spare to save you in an emergency — but if the rubber has already cracked, aged, or weakened, it may be unusable when you need it most.


Because spare tires are rarely checked and often mounted externally (especially on Jeeps, Broncos, CR-Vs, Rav4s, and FJ Cruisers), they dry-rot much faster than the tires you drive on.

Here are the most common signs of dry rot, what causes it, and how to prevent it from happening.


What Is Dry Rot? (And Why It Ruins Tires)

Tire dry rot — also called sidewall cracking — happens when rubber loses oils and flexibility over time. It’s caused by:

  • UV sun exposure

  • Heat cycles

  • Weather changes

  • Ozone and oxygen

  • Lack of use or motion


Dry rot reduces the tire’s structural integrity, making it unsafe even if it looks “unused.”


Signs Your Spare Tire Is Dry-Rotting

Cracks in the Sidewall

The most obvious sign. Look for:

  • Thin surface cracks

  • Deep cracks

  • Web-like patterns on the rubber


If you see cracking, the tire is unsafe.


Faded or Gray Rubber

Healthy rubber stays dark and flexible. Dry-rotted rubber becomes:

  • Light gray

  • Chalky

  • Dull-looking

  • Rough to the touch


This means the tire is losing elasticity.


Hard, Brittle Texture

Try pressing your thumb firmly into the sidewall. A healthy tire feels firm but flexible. A dry-rotted tire:

  • Feels hard

  • Has very little give

  • May flake or dust slightly


This is a major warning sign.


Cracking Around the Bead and Tread

Many drivers only check the outer sidewall, but cracks can also form:

  • At the bead (where the tire sits on the rim)

  • In the tread grooves

  • Near the lettering


Spare tires often dry-rot evenly because they don’t move or flex.


Small Chunks of Rubber Breaking Off

Advanced dry rot causes rubber to separate. If you see chipping or pieces breaking off, the tire is already unsafe.


Tire Cannot Hold Air

In the worst cases, dry rot causes slow leaks or the tire refusing to hold air at all.

A spare tire that can’t stay inflated is completely unusable — even for emergencies.


Why Spare Tires Dry-Rot Faster Than Regular Tires

Unlike your active tires, spare tires don’t:

  • Move

  • Flex

  • Heat evenly

  • Maintain natural rubber oils


Spare tires also remain in direct sunlight for years, especially when mounted on the back of SUVs.


Vehicles most affected include:

  • Jeep Wrangler

  • Ford Bronco

  • Toyota RAV4

  • Honda CR-V

  • Toyota FJ Cruiser

  • Hummer H2/H3

  • Suzuki & Isuzu SUVs


These vehicles have upright rear-mounted spares that sit in full sun every day.


How to Prevent Dry Rot on Your Spare Tire

Keep the Spare Covered

A high-quality spare tire cover blocks:

  • UV rays

  • Rain

  • Heat

  • Ice

  • Road salt


This is the most effective way to prevent dry rot.


A USA-made SpareCover® can extend spare tire life by years.


Check Tire Pressure Every 3–6 Months

Tires naturally lose air over time. Low pressure accelerates cracking.


Clean the Tire Occasionally

Dirt, chemicals, and salt all degrade rubber. Use a mild soap and water — no petroleum-based shines.


Avoid Leaving the Vehicle Parked for Long Periods

Movement and flexing help rubber stay healthy.

If storing the vehicle long-term, check the spare before you drive again.


Replace Old Tires — Even Unused Ones

Most manufacturers recommend replacing tires every:

  • 6 years (ideal)

  • Maximum 10 years


Even if the tread looks new, the rubber may not be safe.


When Is Dry Rot Too Dangerous to Ignore?

Replace the spare immediately if you see:

  • Deep cracks

  • Flaking rubber

  • Chunks missing

  • Air leaks

  • Exposed inner layers

  • Severe discoloration


If you wouldn’t trust the tire for a long drive, you shouldn’t trust it as a spare.


Final Thoughts: Protect Your Spare Before It’s Too Late

Most drivers don’t notice dry rot until they need the spare — and by then, it’s often too late. A simple spare tire cover can prevent 90% of the causes of dry rot and keep your tire ready for emergencies.


A USA-made SpareCover® offers the best long-term protection with marine-grade vinyl, UV-resistant materials, and exact-fit sizing.


Protect your spare tire now — your future self will thank you.

 
 
 

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