What Should I Do if I Have a Slow Puncture?

If your tyre is gradually leaking air but you can't spot any signs of damage, you might have a slow puncture. This guide covers everything you need to know about identifying and fixing the source of a tyre leak.

In a nutshell: If you have a slow puncture, spray soapy water on the tyre and look for bubbles to see where the air is leaking out. You can then fix the puncture using a puncture repair kit.

Why is my tyre flat?

The top causes of a flat tyre are:

• Puncture caused by sharp object

• Failure or damage to valve stem

• Ripped or rubbed tyre

• Tyre bead leaks

• Vandalism

• Tyre and rim separated due to collision

• Overinflated tyres

It's worthwhile noting that if you've accidentally driven around with a flat tyre, the inside of the tube will have been shredded by the wheel, so it will need replacing rather than repairing.

In this instance, if you don't know how to change a tyre yourself or don't have time, you can use FixMyCar to find a mobile mechanic who will come to you.

How can I locate where the tyre is leaking?

Using soapy water, or water alone, can help you determine precisely where the leak in the tyre is. Mix water and soap in a spray bottle and spray the tyre's surface. Make sure you cover the following:

• The tread

• Sidewalls

• The valve stem

• The opening (ensure the cap is removed)

• Along both sides of the rim

Once you’ve covered the tyre's surface, you’ll find the leak by spotting where the bubbles are forming. You can remove the wheel to do this, which makes it easier to spot the leak, or leave it on and turn the steering wheel to expose the inner sidewall.

Another way of spotting a tyre leak is to remove the whole tyre and submerge it into a large tub of water (if you don’t have a big enough tub, then do it sections at a time). When bubbles begin to form in the water, you have found the leak.

How can I stop air leaking from my wheel or tyre?

You can stop a leak in your tyre by using a tyre plug kit or tyre puncture sealants.

However, if you'd prefer the peace of mind that comes with having a professional fixing the leak for you, most garages and tyre centres will repair tyres rather than replace them if it's possible to do so.

How to stop air leaking from your car wheel using tyre puncture sealants

• First, always read the instructions on the tyre puncture sealant tube.

• Pull out any offending objects from the tyre with a pair of plyers.

• Ensure your wheel is at the top of the car by turning it.

• Unscrew the valve cap – this is where the sealant will go.

• Place the nozzle of your sealant onto the valve stem securely and release the contents of the sealant.

• Rotate your tyre by driving your car to ensure sealant is evenly distributed inside, preventing heavy lumps from forming.

How to stop a tyre leak using tyre plug kit

• Using an impact wrench or a lug wrench, loosen the lug nuts. You need to loosen or break the lug nuts before you jack up the vehicle so that the car's weight is still on the wheels. This prevents dangerous spinning when you turn the lugs later on.

• On a level surface, safely jack up the car using jack stands.

• Remove the lug nuts and wheel from the hub using a wrench.

• Remove any offending objects from the tyre with some pliers or follow the above steps to find the leak.

• Clean the hole with a rasp tool to roughen the area, enabling the fix to hold.

• In your repair kit, you will have a plug & insertion tool – thread the plug through the insertion tool.

• Lubricate the plug with adhesive – this will create a better fix.

• Force the plug into the tyre using the insertion tool and let the adhesive dry.

• Cut away any protruding plugs from the exterior of the tyre.

• Pump up the tyre.

• Apply soapy water to the tyre to check if the seal is holding – if it isn’t, add some more adhesive.

• Attach the wheel back onto the car.

• Lower the car, tighten the lug nuts and replace the tyre.

Sealants and plugs are not a long-term solution for repairing your tyre–they last about 100 miles. This type of repair should be used as an emergency repair or quick fix. Book in at a local garage to get your car tyre repaired and avoid future issues.

How do I stop a leak in the bead seal?

A leak in the bead seal occurs when water infiltrates the wheel and sits where the tyre and the rim meet. This area is called the bead seal, and the metal slowly corrodes as the leak is created. Bead seal leaks are most prominent in alloy or aluminium rims.

• Remove the wheel from the car.

• Remove any excess air left in the tyre by putting pressure on the valve stem. This will expose the bead seal area, on both the tyre and the rim. Don’t worry – you don’t need to remove the tyre.

• Get rid of the corroded parts of the rim. This can be done by running a buffing wheel made explicitly for removing corrosion along the bead seal. It polishes the rim, giving it a smooth surface.

• With solvent appropriate for rubber, wipe the tyre area that touches the rim to clean it and help create a better seal when the tyre is inflated.

• On the rim’s bead seal, apply a layer of tyre glue with the tip of your finger or a cotton swab. This isn’t essential but can prevent future corrosion as it will inhibit moisture from penetrating the rim again.

• Inflate the tyre and remount it on the vehicle.

How long does bead sealer take to dry?

Most silicone tyre sealants will take up to 24 hours to dry completely. Check the instructions on your sealant to find out how long you'll need to wait.

If you’ve got a leak in your tyre, find the best garages near you and get quotes for free using FixMyCar – our trusted garage network contains thousands of mechanics who are happy to help. 

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