Water in Trunk Under Spare Tire – Possible Causes & Solutions

Finding water pooled in your trunk underneath the spare tire can certainly be puzzling. The spare tire compartment is designed to be sealed off from the rest of the vehicle. So where is that water coming from?

Identifying the source of moisture is key to preventing potential damage or mold growth. Let’s examine the common causes of water in the trunk under spare and how to address them.

Main Causes of Water In Trunk Under Spare Tire

There are a few likely explanations for unexpected water in trunk under spare tire:

Main Causes of Water In Trunk Under Spare Tire

1. Condensation Buildup

Condensation is the most common source of moisture in the spare tire well. It occurs when warm air meets colder surfaces and condenses into water droplets.

On long drives, the air inside your car warms up. When you park and it starts cooling, condensation forms on cold surfaces like windows and metal panels.

The spare tire well is prone to collecting this accumulated condensate. The carpet liner absorbs it like a sponge.

2. Leaking Trunk Seals

Faulty seals around the trunk lid, tail lights, or rear windshield allow rainwater to enter the compartment around the spare.

Cracked or dried-out rubber seals should be replaced to prevent leaks. Detached sections may also need reattaching.

3. Exhaust System Leaks

Small holes in the exhaust pipes, muffler, or mounts can permit exhaust gases to enter the trunk.

Condensation from the exhaust forms puddles, especially after long drives. The water will have a distinct sulfur smell.

4. Rear Windshield Washer Fluid

Cracked washer fluid reservoirs or hoses can drip washer fluid into the spare tire well over time.

Check your washer pump and lines for leaks if you suspect this issue for water in trunk under spare tire.

5. Trunk Lid Alignment Issues

If the trunk lid sits slightly ajar or misaligned, gaps can allow rain or snowmelt inside.

Have the lid adjusted to sit flush with the seals. Inspect hinges and closures for damage.

6. Leaking Tailgate

SUVs with tailgates can develop leaks around the seals, hinges, or rear wiper mounts. Water then follows gravity down to the spare compartment.

Assessing the Situation

Before attempting to fix the water in trunk under spare tire, make some initial observations:

  • Note if leakage only occurs after long drives, indicating condensation.
  • Check if it correlates with recent rains, pointing to a leak source.
  • Smell for exhaust odors suggesting an exhaust system breach.
  • Look for other signs like reduced washer spray pressure.
  • Check trunk lid alignment and condition of seals.

These clues will help you zero in on the most likely source.

Removing Water From the Spare Tire Well

While identifying the exact cause, take steps to remove standing water in trunk under spare tire:

  • Remove the spare and dry it thoroughly.
  • Use towels or a wet/dry vacuum to extract water from the well.
  • Remove plastic trunk liners and floor mats to dry out.
  • Allow the trunk area to air out completely.
  • Consider drilling a drainage hole if water collects frequently.

Promptly eliminating the standing water will prevent musty smells and potential mold growth.

How to Fix Water In Trunk Under Spare Tire

Once the source is found, permanent repairs can be made:

  • For condensation – Improve ventilation to allow moisture to dissipate. Avoid covering spare tire well.
  • Leaking seals – Replace cracked or detached trunk seals and tail light gaskets.
  • Exhaust leaks – Have the exhaust shop identify and repair any breaches in the system.
  • Washer fluid leaks – Replace leaky washer reservoirs or damaged hoses.
  • Trunk alignment – Adjust trunk lid to close flush with seals. Repair any hinge/latch damage.
  • Tailgate leaks – Replace leaking tailgate seals and bushings. Check rear wiper mounts.

How to Fix Water Under Spare Tire

Fixing the specific deficiency is the only way to reliably stop recurring water accumulation under the spare.

Signs of Bigger Problems

Ignore water in trunk under spare tire well for too long and you could face some expensive complications:

  • Mold growth – Wet carpets are breeding grounds for unhealthy mold. This requires extensive cleaning to remove.
  • Electrical issues – Moisture can corrode trunk wiring and lighting, causing shorts and malfunctions.
  • Rust spread – Untreated water leads to accelerated rust in the spare well, hinges, and latches.
  • Health risks – Mold spores and musty air can cause respiratory issues and allergic reactions.

Water in trunk under spare tire. If you notice mold smells or see visible mold, act quickly to halt its spread. Rust and electrical gremlins can also snowball into big bills.

Frequently Asked Questions

Here are some quick answers to frequently asked questions about water under the spare tire:

Why is there water under my spare tire?

The most common reasons are condensation buildup, leaking trunk seals, exhaust leaks, or leaks from the washer fluid system.

Why would there be water in my trunk?

If water gets in from rain or snow, it will flow to the lowest point – the spare tire well. Leaks, gaps, and seal damage allow the water entry.

How do I find a water leak in my trunk?

Check for alignment issues, cracked seals, or detached liner sections. Leak tracing dye can also help identify the source.

Is spare tire safe in rain?

The spare itself won’t be damaged by water as long as you drain any standing water from the well. Just be sure to thoroughly dry it.

How do I dry out my car trunk?

Remove plastic liners and mats to air out. Place towels or absorbent materials to wick away moisture. A wet/dry vac can also help extract water.

How do I know if my tire valve is leaking?

Check for bubbles around the valve stem using soapy water. Also, look for consistent low pressure in that tire requiring refilling.

What to do if trunk gets wet?

Dry it out completely as soon as possible. Vacuum up water, dry the surrounding carpet, and allow the area to ventilate and evaporate residual dampness.

What is the fastest way to dry your car?

Open all the doors and use fans to circulate fresh air. Baking soda can also absorb interior moisture quickly. Remove and dry soaked carpets.

Can I air dry my car?

Yes, opening the car up to allow fresh airflow is an effective way to dry it out. Just be sure to also towel dry any surfaces where water has collected.


While finding standing water in trunk under spare tire can be alarming, in most cases it simply results from condensation buildup or minor seal leaks.

Identifying the source of moisture quickly, extracting any standing water, and repairing leaks will get the issue under control before major problems arise.

With proper diagnosis and timely repairs, you can keep your spare tire well dry and prevent expensive water damage or mold growth down the road. Just be sure to address any leaks or alignment issues promptly.

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