Home News Slow Leak In Tire: How To Diagnose And Repair

Slow Leak In Tire: How To Diagnose And Repair

by Kelvin Yates

The point of contact between the roads and your vehicle, the tires, is the measure of performance and safety of any vehicle. That means, with a leaky tire, you are putting your life as well as other people’s lives on the line. More deceptively, we have instances of a slow leak in tire.

A slow leak in tire results in low tire pressure, which can negatively impact fuel economy. Ultimately, it can lead to a blowout. It can also decrease the maneuverability of the car, making it harder for you to drive your vehicle in bad weather or handle an emergency.

Today, we discuss how to diagnose and fix a slow leak in tire. Stop avoiding the low-pressure sensor and refer to this guide now!

What Is A Slow Tire Leak?

A slow leak in tire is basically a small vulnerability in the rubber that causes the tire to gradually lose air over a long period. A slow leak is much different from a general leak as you might not be able to notice them unless you’re really looking (sometimes with a microscope).

Unlike other kinds of leaks, a slow leak doesn’t usually give hissing noises and nor is there a dramatic change in tire pressure. Plus, they can develop almost anywhere on the tire, making them so much harder to locate. The tires on your car may get a slow leak:

  • In the tire bead
  • Around the valve
  • On the sidewall
  • In the tread
  • On the valve stem

Although slow leaks aren’t exactly obvious, they can be risky. Over time, the air pressure goes down below safety levels. If this happens while you’re driving, more heat is generated in the tires.

This additional friction and heat can wear the rubber down faster. This issue is more common in common moving at freeway speeds.

It is extremely important to get these kinds of problems resolved as soon as they have been recognized. If you don’t, you run the risk of further damaging your tires.

Signs Of A Slow Tire Leak

Identifying a slow leak is tricky. You have to pay close attention to the performance of the tires. If you notice these signs, your tire may have a slow leak:

  • Low tire pressure when your car has been parked for an extended period
  • Repeated flats despite having one of more tires replaced
  • Only one tire has low pressure while the others are at standard pressure

If you suspect that any one of the tires has developed a slow leak, a basic check can be conducted in your own garage or driveway. In fact, there are three simple ways to check if there is a slow leak in tire.

We will be getting into those three later on but keep in mind that not all slow leaks are the same. This also means that not all of them will be detectable in a certain way.

In any case, a leak in a tire calls for emergency action. Get the tires checked by an expert and have them fixed or replaced.

Possible Reasons Of A Slow Leak In Tire

Wheel Alignment Cost

There could be several reasons to slow leaks in your tire. Let’s find out some of them.

Wheel Problems

The two primary wheel issues due to which there could be a leak in tires include:

Poor Valve Stem

Valve stems are frequently exposed to a cocktail of chemicals while your car is operating. This causes them to deteriorate and gradually leak air. Usually, a new stem comes along with a new set of tires.

But, if the slow leak is more than one to three psi a month, you may have to replace them earlier. Another reason is the over-tightening of valve cores. Ideally, the torque must be approximately 4” per pound. You could need a pre-set wrench.

Damaged Or Bent Wheel

When the wheel constantly hits road hazards or corrodes, it could lose its perfectly round shape. In addition, if there’s corrosion on top of the tire when it’s mounted, the air loss could be greater.

If the wheel is bent, the vehicle could vibrate abnormally, causing damage to the tire’s bead and ending in an air leak.

Tire Damage

When it comes to the tire, there are way too many plausible culprits behind a leak.


Although tires are rather sturdy to resist the wear and tear they have to tolerate daily, a simple nail in its weak spot could cause a puncture. A puncture means air loss at the rate of two to three psi per day. However, if the nail remains lodged in the tire, the air loss could seem insignificant. It still has to be extracted.

Bead Damage

The presence of a sealing surface between metal and rubber could result in air loss. Little pieces of debris between the tire and the rim, bead chunking, and more can create a small hole for the air to escape through. Moreover, age contributes to the breaking of seals, as the rubber loses its elasticity after years of service. That’s why it’s crucial to know the tires’ age before you purchase them.

Finally, due to the work of an inexperienced technician, the bead could sit weirdly on the rim.

Road Hazards

Driving over a curb or a large pothole could flex the sidewalls of the tire and make it lose air. In case there is no damage to the tire-wheel unit, the tire has to be re-inflated. Remember to check for sidewall cuts, bulges, and punctures – indicators of external or internal damage that can contribute to leaks.

When it’s time to take your car for a routine check or you notice air slowly decreasing in the tires, make sure to check for all-around damage. A few smaller problems, like a minor puncture, are repairable.

The Factor of Temperature Change

cost to mount and balance tires

Every time the temperature drops 10°F, a tire loses almost 2% of air. Similarly, it rises 2% every time there is a 10°F rise in temperature. So, lighter passenger cars generally gain/lose about one psi, while buses and pickups could gain/lose two psi.

For the majority of the US, the variation between night and day temperatures is close to 20°F. So, if your car sits outside in the cold for a night and you see underinflated tires the next morning, that’s nothing to stress over. Expect to see the inflation return to normal by the afternoon.

Pressure changes occur due to the temperature change. The air level is still the same. Keep the pressure the same if there is no damage.

Finding The Air Leak

We mentioned three ways through which you could locate an air leak. They are:

Feel Or Sound

In the simplest cases, the leak can be found by feel or sound. A distinct hissing sound can be heard and it intensifies as you move closer to the leak. Feel the tire in that region for any air loss. If the tire is somewhat hot, the leak zone will feel warmer.

Using Soapy Water

Mix 20% soap or detergent with water and pour it into a spray bottle. Spray the solution over the tires and rim edges. Make sure to soak the valve stem first before moving onto the outside and inside edges of the rim. Pour a little of the mixture on the tread and sidewalls to check for damage you may have missed. Bubbles will form where there is a slow leak in tire.

This doesn’t yield instant results; wait for five minutes to see any changes. Refer to this video for detailed instructions on how to DIY this diagnosis.

Dunking The Wheel In Water

Take the wheel out of the vehicle and dunk it in water. Small bubbles will start to be released from the leaky part. Puncture or any kind of damage may be located on the other side, so if there’s no visible reaction after five minutes, flip the tire over.

Generally, the soapy mixture method works best, even for smaller damages. Not to mention how it’s the easiest and most efficient method. Demounting the tire is not even necessary. The method with soapy water usually works to repair minor punctures.

Things To Ask Yourself Before Trying To Patch A Tire

There are three solutions to the slow leak in tire issue. You can patch the hole, use a portable tire inflator to pump the tire up, or put a spare on and purchase a new tire. Instead of filling the tire with air every other day, the best (and safest) option is to fix it with a professional tire plug kit.

But before that, you have to determine whether the tire is safe to fix. Ask yourself the following questions to decipher whether you have an unrepairable case on your hands.

  1. Is there a separation on the tire?
  2. Do you see any cupping on the tire?
  3. Is the tire simply too old to repair?
  4. Is the tread depth too low to fix?
  5. Are you skilled enough to handle a professional tire plug kit?
  6. Have you driven with the damaged tire for a long time?

Repairing Slow Tire Leaks

The repair method will depend on where the leak is and how bad the damage is. For instance, if there is a leak in the tire’s tread, you could make it disappear completely with the help of a mechanic. They will put a patch on it.

In contrast, a leak caused due to a bent wheel could require the replacement of both the wheel and the tire. Similarly, if the reason behind the issue was corrosion of the air valve, you will either have to replace the valve or replace the whole tire.

As slow leaks are kind of hard to find, it’s necessary to bring your vehicle in to the mechanics for evaluation. Home patch kits don’t do enough to entirely fix the damage because small leaks are often related to complex issues with the wheel or tire.

You can stop a leak in the tire by using tire puncture sealants or a tire plug kit.

Using Puncture Sealants

Axle Repair

First things first, don’t proceed without reading the instructions on the sealant tube. Use a pair of pliers to pull out the offending object (s) from the tire.

  1. Turn the wheel so it’s at the top of the car
  2. Unscrew the valve cap as this is where you’ll put the sealant
  3. Position the sealant’s nozzle into the valve stem and drop the contents of the sealant inside
  4. “Drive” your car to rotate the tire. This ensures proper distribution of the sealant inside the tire, preventing the formation of heavy lumps inside

Using Tire Plug Kit

Loosen the lug nuts with a lug wrench or an impact wrench. The lug nuts have to be loosened or broken in before the vehicle is jacked up so the weight of it is still on the wheels. This essentially prevents dangerous spinning after the lugs are turned on later.

  • Use jack stands to safely jack the car up on a level surface
  • Take a wrench and remove the wheel and lug nuts from the hub
  • Use a pair of pliers to remove any breaching objects lodged inside the tire
  • Clean the hole using the rasp tool that comes in the tire plug kit. This roughens the section and enables the fix to hold
  • There will be an insertion tool and a plug in the repair kit – thread the latter through the former
  • Smear adhesive over the plug to create a better fix
  • Force the plug inside the tire through the insertion tool. Let the adhesive dry completely.
  • Check for any protruding plugs from the tire’s exterior. Cutaway if any is found.
  • Inflate the tire. Apply a bit of soapy water to check if the seal has formed – if not, add more adhesive.
  • Attach the wheel to the car before lowering it. Fasten the lug nuts and change the tire.

Plugs and sealants aren’t a long-term solution to leaks – they generally last for 100 miles. Consider this a quick fix. Make sure to make an appointment at the local garage to fix this problem immediately.

Fixing Leaks In The Bead Seal

If water infiltrates the tires and sits still in the juncture of the tire and rim, a leak develops in the bead seal. This zone is named the bead seal area, and due to the leak, the metal slowly corrodes. This kind of leak is most prominent in aluminum or alloy rims. Here’s how you fix leaks in the bead seal:

  1. Take out the wheel from the car: Put pressure on the valve stem to release any excess air left behind in the tire. This will reveal the bead seal area. You don’t have to remove the tire from its rim – don’t worry.
  2. Remove the corroded bits of the rim: There are buffing wheels designed specifically to remove corrosion from the bead seal. This polishes the rim, making the surface smooth. Use that along with the bead seal.
  3. Clean the dirt: Using a solvent made for rubber, clean the area where the tire meets the rim. This will help form a better seal upon inflation of the tire.
  4. Apply tire glue: On the rim’s bead seal, put a layer of glue. You can use the tip of your finger but if you don’t want to touch adhesive, use a cotton swab. While this step is optional, it can prevent corrosion in the long run by inhibiting moisture from entering the rim.
  5. Pump up the tire and remount it on the car.

Fixing And/Or Restoring The Rim

Slow Leak In Tire

If the wheel is bent, we suggest going to a mechanic offering hydraulic assistance. This new method is super-efficient in straightening a wheel. Never take a hammer to the aluminum alloy wheels or you could break them completely. Aluminum is rather brittle; the gentler you are, the better the fix will be.

The best way to approach an issue like this is to clean the wheels so there’s no corrosion. You need to remove the tire after getting the wheel out. After that, gather aluminum metallic polish, sanding tools, and wax (this is optional).

Clean the wheel and remove any grease from it. Then, take off any paint or remaining finishes. Thoroughly sand all the parts, making sure to get between the crevices and inside the holes of the lug nuts. Put the sander on low speed and clean the rim’s center. Polish it till it’s all shiny again and let it dry before applying a layer of wax (if needed).

It is subject to change depending on the type of the wheel and the manufacturer’s specifications. Always make sure to wear gloves and protective glasses beforehand.

Extracting A Broken Valve Stem

You have to let the air out before you remove the tire from the rim. Changing a valve stem is quite simple. All you have to do is release the air from the tire, break its top bead, and screw the valve stem remover tool onto the stem before pulling it out.

A leaking valve core can be fixed with the help of a valve core remover tool. This method is the same as the one you would use to release air from a tire.

Is It Safe To Drive With A Slow Leak In Tire?

You can drive a short distance if there’s a slow leak in tire. But, you also run the risk of making the hole bigger. The larger the hole, the harder the tire is to repair. At one point, it could become non-repairable. As a good measure of thumb, the hole shouldn’t be bigger than the tire plug.

The tire could go entirely flat while driving too, so that’s a consideration. Driving with a flat tire damages it as the rim constantly grinds the tire down. Slowly, the rim could bend out of shape.

Things To Know About Tire Pressure

Slow Leak In Tire

The tire pressure stick will let you know what level is too low for tire pressure. It won’t be the end of the world if it’s slightly lower than the recommended level. However, driving for prolonged periods in that state can be damaging for the car.

When your car runs on low tire pressure, the edges of the tires wear out faster. And if you ride on flat tires, it will destroy the tires completely. On the other hand, riding on over-pumped tires can wear out the center tread faster.

In essence, you have to maintain the tire PSI. Make sure you have a portable air pump in the car at all times.

If your TPMS light is on, get that checked. Some cars don’t have a TPMS system and if yours is one of those, keep an eye on the tire pressure each time you get gas. A tire that has to be inflated frequently is probably leaking.

In addition, tire pressure increases ever so slightly when you’re at the end of your drive, regardless of weather conditions. Since the tires are constantly in contact with the road, the inner air particles heat up and expand.

Diagnosing and Fixing Slow Tire Leaks

  • A leaky tire can decrease fuel economy and put drivers at risk for a blowout, making it essential to diagnose and fix the problem promptly.
  • The three most common causes of slow tire leaks are damage to the valve stem, damage to the mounting surface of the tire, and puncture damage from road debris.
  • A slow tire leak can be diagnosed using the tire pressure monitoring system (TPMS), manual pressure readings, or the “spray method” which involves using soap and water to detect bubbling on the tire’s surface.
  • Slow tire leaks caused by puncture damage can be temporarily fixed with a tire plug or patch kit until the tire can be professionally repaired.
  • A permanent fix for a puncture-caused leak involves removing the tire from the wheel and using a combination plug and patch on the tire.
  • If a leak is caused by a faulty valve stem, it may need to be replaced or the entire tire, while a damaged mounting surface may require replacing the entire wheel.
  • Valve stems can corrode and go bad over time due to use, dislocation, and exposure to chemicals on the road such as road salt.
  • Damage to the mounting surface of the tire can occur due to corrosion over time or from driving into curbs, speed bumps, or potholes.
  • Contrary to popular belief, puncture damage from nails, screws, and debris does not always lead to an immediate flat tire or blowout, as the object usually remains lodged in the rubber, preventing quick air leakage.
  • It is recommended to check tire pressure manually every week or so, even if the car has a TPMS, to ensure the tires are properly inflated and to detect any slow leaks.

Slow Leak In Tire: Bottom Line

The correct tire pressure goes a long way in keeping your car safe. It is also one of the earliest indicators of a slow leak in tire. Don’t ignore obvious signs your car is giving you or it may require some serious repair investments later.

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