Popping A Bead

Repairing the damage caused by airing the tyres down too low.

You can clearly see how the bead has come away from the rim …

Tyre pressure is the key to most of our 4WDing traction. The first thing most people will do is air down before they head offroad. As we all know, airing down will give the tyre more surface area on the track as well as help protecting the tyre from punctures and softening the suspension. Keeping traction will also help to “tread lightly” and stop excessive erosion of the environment.

The big risk of airing down too low – and it will happen eventually if you do it all the time – is popping a bead …

Once you have taken the weight off the rim and have jacked it up, the tyre can be pushed back into shape. As long as the inner bead in still on, you should be able to pull the tyre forwards to make the bead of the tyre contact the rim …

What is ‘popping a bead?’

The wheel rim is designed with an outer edge to suit the bead or inner edge of the tyre. These two edges are an interference fit and when air pressure pushes these two edges together it actually seals the tyre onto the rim.

The problem when letting the air out of our tyres is that we have less pressure keeping the edge of the tyre pushing out, which makes the tyre more susceptible to separating the sealing edge of the tyre from the wheel rim. This is what we call ‘popping the bead.’

It happens most typically when the tyres pressures are low, hitting wheel ruts with too much speed, and it can also happen quite easily when driving on sand and turning sharply.

Low tyre pressure under 15 psi is much more susceptible, other factors include speed, and the loads carried on the 4WD.

So what can we do to get going again?

In most cases it will only be the outer bead that has come off, but if you have to drive a bit to get to safe level ground then you can end up separating the inner bead as well, which makes things a lot harder.

One of the easiest things to do is to just fit the spare tyre, but when out touring this solution could be the wrong one, because the spare might be needed if another tyre gets seriously damaged.

The first thing I would try is to reinflate the tyre and try to get it to seal again;

– You will need to jack up the 4WD and take the weight off the tyre.

– Then clean out any mud or debris from between the rim and the tyre.

– Once cleaned, use the air compressor to pump up the tyre.

– While inflating, also hold the back of the tyre and pull it forwards to close the bead of the tyre onto the rim.

– If you can catch the seal then the tyre will begin to inflate and it will pop itself back into position on the rim.

Look closely and you can see that the top of the inflating tyre is almost ready to pop itself back into place. The bottom is seated but once the top seals as well it usually goes with a bit of a bang and you really don’t want your fingers anywhere near it.

This is where an air tank could come into its own; as to reinflate the tyre you will need a large volume of air initially to try to get the bead of the tyre to ride back up onto the rim.

Other than that, the ARB twin compressor would also be an advantage. It is possible to get it with a standard compressor but it might just be a lot harder.

Removing the valve will help with inflating as it can allow a larger volume of air into the tyre. Don’t get me wrong though, to get the tyre inflated again can be time consuming and a lot of hard work – there will be tears!

Out on the tracks this is probably the safest way to reinflate a tyre that has popped a bead. There are many other techniques but they are not as safe so I can’t recommend techniques in an article like this, apart from saying that sometimes you have to do what you can to get going.

It’s just important to always be prepared and carry a good spare tyre and rim, if not two. Make sure you have an air compressor and a decent enough jack capable of lifting a wheel completely off the ground. Whether it’s an exhaust jack or a high-lift jack, you must also know how to use it safely.

This is one thing I hope never happens to you, but if it does, I hope I’ve been able to help.


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