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  • Slow Tyre Leaks: Warwick Demmocks

Ask an Expert: Slow Tyre Leaks

It was Wednesday evening. The plan was to take the bikes down to the local river so I could practice various off-road riding techniques. Unfortunately, I remembered the TTR250 had a very slow leak in the front tyre that I hadn’t got around to sorting since its last outing – I know – bad Jess!

We had a tube we could put in it, but we were only planning on a short outing. Perhaps it would be okay, or perhaps it would leave us doing a roadside repair in the diminishing light.

Me being me, I first consulted Dr Google and adventure forums. I like to wade through the misinformation and see if I can pick out the common themes. There were many people whose choices were based only on their personal experience, not on what could happen. However, I did receive a comment on one of the forums that I felt was especially applicable, especially for new riders. This came via a Facebook adventure group:

“I will tell you to always follow your gut and ride your own ride. It’s true, a short ride can be OK. But that’s not the point . . . Don’t ever feel pressured to do something you aren’t comfortable with. The reality is that worry[ing] about your gear or equipment can leave you distracted. Distracted and worried makes your ride stressful, and that’s never a good thing . . . I know plenty of people who don’t carry [repair kits/spares] for ‘day trips’. I don’t ride that way. It’s just not how I feel comfortable. I’d rather be ready.”

Even for day trips, take a repair kit with you to avoid a long walk.

After scouring the great and vast interweb for information, I decided to pick the brain of tyre industry expert and friend, Warwick Demmocks.  

Warwick worked several years in a rural garage repairing motorcycles and has had bikes of all kinds since he was young. He has a combined motorcycle and car tyre industry experience of over 35 years. Much of his experience has been in a hands-on management role at an international tyre company - where he still works. When it comes to applying car tyre knowledge to motorcycles, he explains, tyre repair is really the only aspect that has commonalities to both vehicles. When working on motorcycles though “two tyres on a bike are more critical than 4 tyres on a car" he says, emphasising the importance of getting bike tyre repairs done right.

He's a good person for me to launch all my questions at.

The expert advises getting comfortable with changing your tyres and tubes at home first before going on your adventure. But I think this guy has more problems than just a flat...

What do you do when you know or suspect you have a slow tyre leak?
Ideally, you’d replace the tube if it’s a tubed tyre, or plug the leak if it's a tubeless tyre. Slow leaks are more common in tubeless tyres as they tend to try and self-seal, whereas tubed tyres tend to just deflate quickly. If you can't fix it, keep it inflated (this may mean stopping frequently to pump it up) and get to a place where it can be repaired. Slow leaks can become fast leaks and you never know when this can happen. It could be a long walk for you!

If I ride with a slow tyre leak, how can I expect the bike to respond?
As the pressure drops, the handling will become sloppier - steering will be less responsive.
Is it safe to ride with a slow tyre leak?
If you’ve got a way to check and maintain the pressures, yes, but avoid riding with a slow leak if possible as there is no way to know when and if it may become a fast leak - leaving you stranded.

How do you find out where the leak is coming from on a tubed tyre?
- Check the tyre externally for any foreign object such as a nail or wire that might be penetrating the tyre
- Strip the tube from the tyre and submerge in water. Look for bubbles that will indicate escaping air.
- You could try and inflate the tube and feel for any escaping air, but this is unlikely in the case of a slow leak.
- Check the valve core for leaks you can apply soapy water, or saliva (if you’re in the boonies), around the valve and check for any bubbling

How do you find out where the leak is coming from on a tubeless tyre?
- Check the tyre externally for any foreign object such as a nail or wire that might be penetrating the tyre
- You can use soap water and spray on to the tyre (while it’s still on the bike) and check for any bubbling
- Check the valve core and stem for leaks as per the tubed tyres. Tubeless valves should really be changed each time the tyre is changed, depending on whether they are snap in or bolt in ones. The latter don’t generally need changing every time but check the nuts and rubber seals. These can potentially leak

What are common causes of slow tyre leaks?
- External puncture through tyre and/or tube making a small hole
- Tube chaffing foreign matter inside the tyre (tubed tyres)
- Debris inside the valve core
- A cracked valve stem

What can I do to reduce the likelihood of getting a slow tyre leak?
- Keep your tyre pressures constant
- Fit new tubes when you fit new tyres
- Run tyres with plenty of rubber – the less rubber, the easier it is to get a puncture
- Use metal valve caps – if there's any debris in the valve core causing a leak, a metal cap should prevent the air from escaping

This will be me soon. Except I might be using the mallet to hammer expletives into the lawn.

What kit do I need to deal with a slow leak in a tubed tyre?
Replace rather than patch a tube. Patch it if you have no choice then replace it when you can. For the sake of $15 – $30 it makes sense. For a full kit you'd ideally have:
- Tyre levers, X2
- Tools to remove the wheel
- Tubes, front and rear. I recommend using standard over heavy duty for on-the-road repairs as the thinner tube is easier to fit, smaller and lighter to carry
- A tube repair kit if you end up just patching the tube. They should contain: rubber cement, patches and abrasive
- A pump or gas canisters
- Valve core tool and spare valve core

What kit do I need to deal with a slow leak in a tubeless tyre?
- A tubeless tyre repair kit – a plug kit. These usually contain: ream tool, rubber solution, rubber plugs, hook tool for plugs, knife, and 3 x CO² canisters. It’s important to note that with tubeless tyre repairs these are definitely temporary and you should visit your nearest motorcycle repair workshop ASAP
- Valve core tool and spare valve core/or spare snap in valve
- Tyre levers, a tube and tools to remove the wheel (if you want the option to fit a tube as a temporary fix ie for unpluggable repairs)

Me, knowing I have to master this skill, but also knowing how it's going to pan out...

If you're planning on a trip, Warwick recommends practicing changing tyres and tubes at home first, so that you feel confident doing this with no help around. 

Well, guess what I’m doing tomorrow? That’s right. A lot of cussing.

Also, you can read this article on equipment for punctures and puncture repair when on the trail.

Author of this article: Casper