Tyre losing pressure

[Ian222]

Ok so I noticed the rear tyre losing pressure slightly, it was getting low in terms of grip so I bought a new tyre same brand (maxxis) but got assegai instead. Changed the valves as well and cleaned it all and put in new sealant and it’s still doing it, I then sprayed a soapy solution around the rims, tyre and valve and no sign of any bubbles so what could it be. The other wheel all seems fine. So what’s peoples first thoughts on this? If it’s the rim tape at fault wouldn’t it show leaking air through the spoke nipples??

 

[Paulquattro]

Rim tape
And not necessarily going to show through spokes as there is a lot of space to fill in the wheel void first presuming you have alloy rims not carbon

 

[E Bob]

How fast we talking ? Tubeless set up does lose a bit of air over few days, i put a pump on mine every time i ride, even if its daily..

 

[Ian222]

Yes alloy rims.
Rim tape was my thought.

I suppose it loses 2-3psi a day. The other rim doesn’t do it so I can only assume it’s the rim tape.

 

[vertrkr]

Best way is to put it in a tub of water and look closely. A slow leak is sometimes hard to see with soap/water method.

I fought a slow leaker and it turned out it was sidewall porosity that wouldn't seal. I was using 200ml of MucOff sealant, vigorous shaking, laying on the side for hours, nothing worked. I switched sealant to OKO MagicMilk and it sealed right up. Not sure what to make of it but I'll be sticking with MagicMilk.

 

[Stihldog]

My first thought was rim tape also. Air may not be escaping through the spoke holes, rather the very small hole (s) on the rim. It can be difficult to detect but if there is a very small hole in the rim tape, air will escape through the rim side hole. Soap and water usually detects this.

 

[Mikerb]

Every tyre I have ever set up tubeless loses pressure over a few days. The rear always more than the front probably because it is under more stress on a ride than the front despite being a DD v Exo+ on the front. The sealant seals up the tyre walls but then when used the tyre walls flex and partially breaks some of the seal. Just normal. Only tubes hold air for longer as long as they are not punctured!

 

[Ian222]

Ok thanks guys, I will keep an eye on it.

 

[irie]

Yes alloy rims.
Rim tape was my thought.

I suppose it loses 2-3psi a day. The other rim doesn’t do it so I can only assume it’s the rim tape.

Have exactly the same wheels, tyres, valves, tape and sealant on both wife and my bikes. Both front Schwalbe Magic Mary Super Gravity lose perhaps 1 psi per day and both rear Maxxis DHR2 DD lose perhaps 2 psi per day.

 

[steve_sordy]

I have similar pressure losses on my tyres and all previous tubeless tyres, except the Mavic UST ones I had when I first went tubeless in 2010. Mavic were the tubeless innovators and their tyres were designed to hold pressure without sealant. But of course, I used sealant because despite their tyre's high quality they could still puncture!

 

[RustyIron]

I suppose it loses 2-3psi a day.

There's nothing particularly abnormal about that.

 

[E Bob]

tubeless is definately the way to go.. A punture can be plugged in seconds trail side, no need remove tyre. Tubes fail, regular too.. I'v allways got a few minutes spare to check my pressures with a pump pre ride. Tubes are ok for canal slayers, Tubelss needed for riders that bash there tyres about some...

 

[RustyIron]

Really?

Why would you bother with the expenses of tubeless tyres when that's the case?

I've not pumped my tyres in almost a year now...

Really?
You have a real Mountain Bike? And you ride it?

You only pump up your tires once a year?
I'm replacing tires every two or three months.
Can you teach me your secrets?

 

[KnollyBro]

Really?
You have a real Mountain Bike? And you ride it?

You only pump up your tires once a year?
I'm replacing tires every two or three months.
Can you teach me your secrets?

Seriously? I have a REAL mountain bike and I NEVER have to put air in my tires!

Real men use SPACE! No more flats, no more pumps, saves weight, adds 2" of suspension and has the added benefit of a nice breeze which blows up between your legs on a hot day. NOTE Not suitable for muddy conditions.

 

[Bones]

Throw some more sealant in it and stop worrying about a small air loss.
So long as it stays up for the ride then it's ok.
It also gets you into the habit of checking tyre pressure regularly.

 

[EMTBSEAN]

From my own experience when I had my old WTB wheels and gorilla tape ghetto method I had no issues with pressure loss and I went months without any loss of pressure whatsoever, now I have Hope Fortus wheels, new tyres, Muc-Off tape and Stans sealant and I have to pump my tyres up each time I go out, my tyres still loose pressure even when I don’t ride for long periods of time

 

[Stihldog]

My method for testing psi has changed. I use the pinch n grab method now. I’m usually accurate to within a few psi.


It’s taken a few years to develop a certain sensitivity for this test. Over time I got tired of using a psi gauge and seeing the same pressure readings every time.

I may have punctured my tires a few times but the sealant quickly seals that. I’ve also “burped” the tires on the rocks but a CushCore on the rear has helped me limp home.

 

[Mikerb]

If you are not setting tyre pressures before each ride I think you are missing a trick or two. Pressures will vary a little with temperature and I have 3 sets of pressures I use depending on the ride ahead and predicted trail conditions. I find the tyres are very sensitive to even just a few psi difference in terms of the performance they offer.

 

[Ian222]

Interesting responses, reason I asked was because it’s not happened until recently and have had the bike over a year. So assumed it was something I had done.

 

[steve_sordy]

Interesting responses, reason I asked was because it’s not happened until recently and have had the bike over a year. So assumed it was something I had done.

You have probably had a load of punctures without noticing, because the sealant did its job. Sealant does not last forever; it goes off and doesn't work; it also can run out if you have had lots of punctures!

When my regular pressure loss starts to increase, I know it's time to top up the sealant.

Check your sealant levels.

 

[Ian222]

You have probably had a load of punctures without noticing, because the sealant did its job. Sealant does not last forever; it goes off and doesn't work; it also can run out if you have had lots of punctures!

When my regular pressure loss starts to increase, I know it's time to top up the sealant.

Check your sealant levels.

Brand new tyre and sealant so should be fine.

 

[jonmat]

tubeless is definately the way to go.. A punture can be plugged in seconds trail side, no need remove tyre. Tubes fail, regular too.. I'v allways got a few minutes spare to check my pressures with a pump pre ride. Tubes are ok for canal slayers, Tubelss needed for riders that bash there tyres about some...

Not if youve forgotten your reading glasses and stick the needle in next to the puncture and make another puncture. Then run out of CO2 cartriges after 3 fills.

 

[E-MAD MALC]

I would knock up some thickish soap water and run it around all the spoke holes and valve and watch a few minutes to see if you get bubbling
If you do I would reck taking the old tape off cleaning the rom and putting putting three rounds of rim tape back on down the centre and one each side tight to the inside edge of the rim it the only thing it could be if the tyre and valve are holding up

 

[Stihldog]

I would knock up some thickish soap water and run it around all the spoke holes and valve and watch a few minutes to see if you get bubbling
If you do I would reck taking the old tape off cleaning the rom and putting putting three rounds of rim tape back on down the centre and one each side tight to the inside edge of the rim it the only thing it could be if the tyre and valve are holding up

The small hole (s) on the side of the rim can be difficult to detect any air escaping. Sometimes, unless you pass your soapy index finger back and forth over the hole, small bubbles will not form.

When I see this I suspect the rim tape. The tape could be installed incorrectly or your finger nail may have accidentally punctured the tape …on any of the inner spoke holes. A small slice at this point is difficult to see and can act as a “duckbill” valve. Almost impossible to seal.

I use a cloth or towel to press the tape into the channel, then press out any trapped air bubbles. I use a heated awl to create a hole for the air valve. I wiggle and rock the valve as I tighten it into place.

Over a 2-3 month period I might lose a few psi. But if the tire leaking …I will find that, or change the tire.

 

[E-MAD MALC]

Went they seat car tyres they use a thickness sealer
I was wondering about using car rim seal to get airtight seal plus the stuff basically sticks the tyre bead and rim together on the wheel
After all you don't put that's all you use in a car tyre
Admittedly bike tyres are more ceceptable to punchers being there light construction
Just a thought