Tires slowly lose air.

So I had new tires put on last by a local bike dealership. Both the front and back slowly lose pressure. After about two weeks they are around 10 psi low. After a month they are nearly flat. They appear to be losing pressure at a similar rate. I cant hear them leaking and there's nothing noticeably wrong with them. They also lose pressure whether the bike is up on the the center stand or not.

Any advice would be appreciated.

Thanks fellas.

 

Corrosion on the alloy where the bead seats or faulty valves? Unusual for both to be affected though.

 

Yay. What are my options and where should I start?

 

How can the valve be leaking if I keep the caps on?

 

Take it back to the dealership and get them to fix it

 

Your issues are either as Franz described, or you have a leak around the valve stems, alternatively through the valve cores themselves. Either way, your dealer did a poor job IMO - they should either have informed you that you needed to clean the beads on the rims or offer to clean them (for a fee, perhaps, although it doesn't take long). Perhaps they are willing to rectify it free of charge if you ask nicely?

But first I would learn where the issues are. Mix a little soapy water (like you are doing the dishes, or blowing bubbles), pump the tires to about 20 PSI, then use a brush to smear the mixture around the beads, where tire meed rim. If you see bubbles, you know the result is dirty - or possibly scored - beads inside the rims. Also, just to make sure, brush around the valve stems where they meet the rims, and remove the valve caps and put a tiny dab on top of the stems as well. Again, look for bubbles. Remember to blow out the water from the valves before refitting the caps, and wipe off all soapy water from the wheels.

 

Because not all caps are full air tight as it is not their primary task - it is to protect the valve cores from the elements. Secondary task is to slow a leaky valve core, and to prevent substantial loss of pressure at very high speeds, speeds that can force the valve core to open.

 

Kickaha, is it realistic they would do anything? I paid for a tire change almost a year ago.

 

I think air can still escape even with the caps on.

 

After almost a year I highly doubt they would. If is started right after they replaced then you would have a case.

As previously mentioned the caps are to keep debris out of the valve core, not to keep air in.

You need to get some soapy water and see where it is leaking from. Loose valve core can leak, easy to tighten with the correct tool. Rim leaks will require removing tire and cleaning up rim, re-seating the tire.

 

What's the tool I need? Anyone know of a pervious thread with some info on how to tighten a loose valve?

 

Has anyone tried overinflating tyres slightly to try and seal the bead? Might work then reduce pressure to the correct pressure before riding bike.

 

I have done that, often it is enough to go to anywhere between 35 and 40 PSI to get a decent seal, which you can usually run fine on unless you are out to grind away footpegs in the twisties. However, I prefer to take the tire off and clean the beads these days, marking the tire/rim so I can refit without having to balance the wheel again (although I will verify before putting back in bike).

 

Many valve caps incorporate the tool you need

 

https://www.amazon.com/gp/product/B0020T17J2/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1

 

The same tool is used on bicycle tires. Same exact valve core too.

 

Before you go cranking the valve cores down, did you hit the tires with soapy water yet to find out where the leak is?

 

Your aluminum wheels could be porous It's not uncommon really My Toyota wheels were that way.
I had them blasted and powdered coated, and that solved the problem.
Cheers, 50gary

 

Oblivion, I am going to do the soapy water test tonight.

Gary, I hope you are wrong because that sounds like quite the hassle.

I am also going to try over inflating to 40 psi because why not.

Thanks, guys!

 

No it is not, but you didn't mention that it had been that long in the original post

What bike and are the wheels marked tubeless ?

 

1986 Radian yx600. I believe they are tubeless. I am normally wrong about things tho.

 

Rims are tubeless.

 

It's very likely the tyre shop didn't clean the bead seats properly - very few of them do a proper job of it.
The result is ususally a leak sometime further on, just as you've found.

Then there's the possibility the tyre shop didn't check / replace the valve stem or the seals on it - again, hardly every happens. Who knows how many bikes are running around on 30 and 40 year old valve stems, just waiting to leak. Ancient valve stems are easy to refurbish, but they don't bother.

There are a flood of sub-standard valve cores on the market, might be that's the fault.

You need the soapy brush.

Right now I'm being plagued with a slow leak on the front, and I'm my own tyre shop - lazy bastard in it.

 

As others already mentioned, its either the bead seats, inside the rims, or its the valves/cores, or some of both.

I had this issue on my rear tire, so at the last tire change I removed the tire myself and thoroughly refinished the bead seats - not fun but not too difficult. There was a nasty layer of hardened goo, probably years of bike shops throwing glue over the rough bead seats to make the tire seal. I replaced the valve then I took it to the shop to mount a new tire (that's a small expense I don't mind).

If it were me, and the tires have plenty of life left, I would consider removing them and doing the above.

 

I am always way slow at mounting new tires on wheels but it is because I am pretty anal about cleaning the wheels before the new tires go on. I generally use scotch brite pads all the way around to get the old goo and corrosion off.

 

Aluminum Wheels can have porosity and thus slow air leaks? I had some Toyota wheels that had that problem. Had them blasted and powder coated (on the inner surface as well) solved that.
Cheers, 50gary