Can wheels be porous?

[nastyjones]

I've put 2 new tires, on my 1st generation gsxr rim in the past 3 years. Both times the tires have lost pressure, about 10 lbs a week. They've been professionally mounted, bead cleaned, new valve etc. I have come to the conclusion that the air is escaping through the rim itself. The tire comes off tomorrow. Should I coat the inside of the wheel with something to help seal it? If so, what is a good choice?

[Nessism]

How about dunking the wheel/tire assembly in water and finding the source of the leak?

[nastyjones]

How about dunking the wheel/tire assembly in water and finding the source of the leak?

That's definitely old school, lol. Actually, I might try that, but feel that the leak is so slow, it might not show up. Worth a try though.

[Steve]

... but feel that the leak is so slow, it might not show up. Worth a try though.

10psi per week is not exactly "so slow".

.

[nastyjones]

Well, I check my tire pressure weekly anyway........ doesn't everyone, lol?

[tkent02]

Only the leaky ones.
Wait, I don't have any leaky ones.

[GregT]

The answer to your initial question is yes, they can be porous. looks to me like you've got either 750 or 1100 J model rims on. They would be powdercoated from the factory when new which would have sealed the casting. If the coating on the inside has been removed or damaged they could well be porous now.

Marvics and Dymags to quote just two "real mag" wheel makes were always either painted or powdercoated as they were notoriously porous.

If you can live with it, fine. Otherwise next time you have the tyres off, think about recoating the rims...

[eil]

10psi/week means you have a leak either somewhere around the bead or a bad valve. Shouldn't be hard to locate.

[posplayr]

My 88 18" 3 spokes were stripped with AC stripper and sprayed with por-15 clear. Isis not take any precaution to spray the insides of the rims. I always make sure the inside of the rim is clean using either a pot scrubber or something equivalent. Mine do not leak except maybe after a year down a few pounds. So while having the interior of the rim powered later might impove leak down 10lbs per week sounds like corrosion on rims (something I have had and fixed with clean up)

[chuck hahn]

I agree with the wheel bath to see where its leaking...like they have at tire stores. That way youre gonna see the rim, beads, rubber, valve stems fully under water. The leaks will show themselves readily.

[Gregory]

I also would do the wheel bath but since I hate dismantling the bike and live close to a lake I would just ride down there see if I could find a safe non slippery shallow area or boat launch to play around in until I found the bubbles.

[Highway_Glider]

I also would do the wheel bath but since I hate dismantling the bike and live close to a lake I would just ride down there see if I could find a safe non slippery shallow area or boat launch to play around in until I found the bubbles.

Could you please find a friend to "Tape" you?

I would love to see that?

[Rhopper]

I converted my 79 Gs750 to tubeless years ago. Porosity was a concern as I've had wheels leak in the past. I painted several coats of clear lacquer inside, masking the bead area. Ten years later, no leaks. I still check tire pressure every ride, but rarely have to add any.

[Crankthat]

Over inflate them.
Then dip and try and find the leak.
If it is the bead or where the stem seals that may not work.
Anywhere else you should see results.
I really do not know how much pressure is sensible for this.
When you start to get scared you are over due to stop inflation.
Post a video if you have fingers still

[Brendan W]

Never needed to dip them. A strong solution of washing up liquid in water brushed on the wheel/tyre/valve will find most leaks. 10 psi a week should be in your face. Are we talking back tyre only and what size is fitted on what rim and was that rim originally tubed and modified for a bigger valve?