Tire Slow Leak: Here’s Why It Happens

Reviewed by

Richard McCuistian, ASE Certified Master Automobile Technician

Technical Reviewer at CarParts.com

Written by CarParts.com Research Team - Updated on September 19th, 2023

Reading Time: 5 minutes
Summary
  • A slow tire leak is a minor but gradual loss of air pressure in the tire. The possible causes of slow tire leaks are tire holes, regular wear, issues with the valve stem, and leaks near the tire bead.
  • If your vehicle has a tire pressure monitoring system, it can indirectly detect a slow leak.
  • You can locate the slow leak on the tire by listening for its hissing sound, spraying soapy water on the part, or asking a professional to inspect it.
  • Driving with a slow-leaking tire is unsafe because the damaged part is more likely to blow out. You can fix a tire leak in the rim with sealant from a plug-and-patch kit, but other issues will require different solutions.

Slow leaks can come from a puncture in the tire, a valve core issue, or between the tire and the rim. All tires slowly lose their pressure over time due to molecular bleed-through where the air leaves the tire through the rubber.

Leaks can cause your tires to be underinflated or flat. This situation will not only reduce the lifespan of your tires but also affect your vehicle’s fuel economy and ride comfort. Learning what causes slow leaks and how to fix them will help make this issue bearable. 

What Is a Tire Slow Leak?

A slow tire leak happens when your tire’s pressure goes down gradually. 

Some sources say the tire leak is considered “slow” if you’re only losing 1 to 3 PSI a month but that level of pressure loss is normal. In reality, most vehicle owners consider a tire leak “slow” if it has to be aired up once a week.

Unlike a big tire puncture that’s easy to see, you might not notice any signs that your tire is losing air until it gets underinflated or flat. 

Furthermore, a tire will generally look okay just glancing at it even if half the air has leaked out.

A leaking tire | Image Source: Richard McCuistian

What Causes a Slow Tire Leak?

It can be challenging to identify the cause of a slow tire leak. Let’s look at the different issues that can cause it in detail:

Tire Holes

One of the possible reasons why your tire is slowly leaking air is a tiny hole or puncture.

As you drive your car, nails, shards, and other sharp objects can damage your tire. Since the punctures these objects make are small, you might not notice them at a glance.

Most of these objects can also get stuck on the surface of your tire, allowing only a small amount of air to come out of the puncture.

You shouldn’t ignore small punctures even if they only cause your tire to lose a little amount of pressure because the situation can get worse anytime. The sharp object clogging the hole can fall off or damage your tire even more, increasing the air it releases.

New tires are more puncture-resistant than old tires because they have thicker threads. But deep threads can also route the sharp debris into your tire, increasing the risk of tire damage.

Normal Wear

A top-notch all-season tire can last around three to five years. So if your tires are older than that, it’s normal for them to exhibit signs of wear.

Some old tires can have cracks, causing air to leak out. If this happens to your tires, you’ll have to replace them immediately.

Valve Stem Issues

Valve stems contain the air inside your tires. They are also crucial for tire pressure because you can put and release air pressure through them. So if one of your tires’ valve stems doesn’t seal properly, it’ll cause air to leak.

A typical valve stem has a valve stem core and cap. If the cap falls off, debris can get lodged in the core, causing valve stem problems. It’s also possible for your valve stems to become brittle or corroded due to moisture and the elements.

Leaks Near the Tire Bead

A tire bead connects the tire to the rim. The seal between the tire and rim is important for proper inflation. Unfortunately, it’s not uncommon for leaks to occur around or near your tire bead.

If you’ve recently been involved in a crash, damage in your wheels and wheel rims can cause leaks near the tire bead. Rim corrosion can also cause a similar issue.

Tire Pressure Monitoring Systems

If your ride was manufactured from 2008 onwards, it likely has a tire pressure monitoring system (TPMS). The TPMS has air pressure sensors that are usually attached to the valve stem assembly of each tire.

The TPMS warning light on your dash will illuminate once the system detects that one of your tires needs to be inflated. Inflating your tires to the recommended PSI will usually solve the issue.

If your ride was manufactured from 2008 onwards, it likely has a tire pressure monitoring system (TPMS).

But if you encounter the TPMS light even after inflating your tires, you might be dealing with a leak.

How to Find a Slow Leak In a Tire

Here are some ways to identify the location of the tire leak:

Inspect the Tires

You can find a tire leak by looking for a hissing sound, which is usually a sign that air is being pushed out of your tire. So listen to the sounds around your tire while you inspect it to determine where the leak is coming from.

Use Soapy Water

Minor leaks don’t always make a hissing noise. Another way to identify the location of the leak is by spraying a soap and water mixture onto the tire. You’ll soon notice bubbles in the area where the leak is.

Contact a Professional

You can always ask a professional to inspect your ride’s tires if you suspect air leaks. A trained mechanic will know how to diagnose the issue and rule out any other problem that might be causing your TPMS light to illuminate.

Is It Safe to Drive with a Tire Slow Leak?

Although it’s technically possible to drive your vehicle with a slow leaking tire, it’s highly recommended that you don’t.

No. Although it’s technically possible to drive your vehicle with a slow leaking tire, it’s highly recommended that you don’t.

Punctured or worn tires are more likely to blow out, increasing the risk of accidents while on the road. Even if the small leak isn’t causing any issues, it can develop into a major leak if you ignore it. So take your ride to an auto repair shop right away if you suspect a leak.

How to Fix a Tire Leak

How to fix a leak depends on what’s causing it. If it’s due to a problem in the rim, a sealant might solve the issue. If you’re an experienced automotive DIYer, a “plug and patch kit” might help. However, it’s a different story if components like your valve stem are causing the issue.

Should you have your tires repaired or replaced? It’ll be best to consult licensed mechanics to find out. They’ll know what to check to know if your tires can still be repaired or if it’s time to buy a new one.

About The Authors
Reviewed By Richard McCuistian, ASE Certified Master Automobile Technician

Technical Reviewer at CarParts.com

Richard McCuistian has worked for nearly 50 years in the automotive field as a professional technician, an instructor, and a freelance automotive writer for Motor Age, ACtion magazine, Power Stroke Registry, and others. Richard is ASE certified for more than 30 years in 10 categories, including L1 Advanced Engine Performance and Light Vehicle Diesel.

Written By CarParts.com Research Team

Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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CarParts.com Research Team and Richard McCuistian, ASE Certified Master Automobile Technician