Alloy wheel rim condition/bead seal

[Torment]

Can anyone identify what could have cause this to the edge of Alloy wheels?

Is it a manufacturing fault or have wheels been damaged previously and poorly prepped prior to painting.

The inner flat of the bead looks to be ok and so does the inner sidewall of the bead, although the scuff/roughness does kinda curve down onto the inner bead sidewall at the top.

Initially prior to photos, the scuffs had been painted, although I’ve flatted the inner sidewall of the bead, which has removed some paint from the damaged edges.

Also, would such a condition of the edges of alloy wheels cause the tyre bead no to seal sufficiently ?

 

[eljefino]

Every used aluminum rim over five years old I've ever had has those "pits."

The seal is primarily on the flat spot where you see the rubber remnants though the vertical side also helps.

Those bead sealing surfaces look satisfactory to me. Did you put soap bubbles on the assembly before you blew it all apart?

 

[Torment]

Yeah, used a washing up liquid water solution to ease separation; also to identify bead leaks just prior to separating.

Yeah, I thought the flat of the bead looked ok.

Thanks for prompt reply

 

[BlueOvalFitter]

It's just minor pitting. When tires are installed, the rim is lubed prior. It could be the lube causing it or the bead with chemicals in the rubber.
I used to see it a lot at my uncle's full-service gas station and at his tire store as well. The only time I had seen it very bad was when the bead would leak. We had a liquid rubber like seal we put on the edge of the rim to seal the tires bead.

 

[Torment]

Yeah, I plan to use a bead sealer when reinflated; I've also replacing the valves.

I've never seen such pitting or deformaty on Alloy wheels before, so wondered whether it could be the cause of the bead leaks.
The unevenness looks too deep to be ground out and probably require precision machining on a lathe, if feasible.

 

[eljefino]

If you hit the pitting with a wire brush then follow up with 80-grit sandpaper, you'll still have the craters, but they'll be smooth enough the tire can deform to fit.

And besides, it's pretty much outside the air-seal zone.

In your case I'd just try to clean that rubbery stuff with a roloc disc or scotchbrite. Don't take too much off, you'll want these rims to last.

 

[Torment]

For time being I'm leaving the pitting as it is; its only on the top flat edge of the inner rim and when the tyres inflated it's hidden from view.
I've lightly flatted the edge all around to remove the roughness.

The inner sidewall/upright of the bead and the flat of the bead are now smooth and clear of any remnants and rubbery stuff.
I've flatted by hand using 120g Emery cloth.

As the wheels are all leaking at the base of the valve stems, when the new push fit rubber valves stems (TR413) are fitted, as an extra precaution, I will also seal the valve stem bases with bead sealer, although I'm curious as to where the valve stem actually seals within the rim.

Does the valve stem actually seal within and around the recess within the wheel (where I’ve typed SEAL HERE on the image) or is the seal made where the bulbous base of the valve stem sits on the rim or maybe both ?

 

[CapriRacer]

I've seen that before and attributed it to poor metal treatment during manufacture.

But you said you painted them. Did you mean clearcoat? Why did you paint them?

Could that be the source of the leaks? Could be. As has been pointed out, the seal takes place on the flat not the side of the flange. Depending on why you painted them, the diameter of that flat area could be too small to get a good seal. That is supposed to be an interference fit.

 

[Torment]

No, I never painted the wheels, I've never had the tyres off.

They've been painted prior to my ownership and judging by condition of the paint on the bead, the wheels have never been restored to the extent that the inside of the rims have ever been painted, it looks to be the original manufacturers paint, a very flat grey primer, maybe epoxy, not powder coat or clearcoat.

 

[ford46guy]

I have an 11 F150 and the wheels had bead leaks. When they took them off it looked like that. They put that black stuff on and it sealed up.
I thought the last place took an angle grinder to the rims :lol:. Aluminum wheels have some clearcoat damage/AL corrosion. Slowly restoring them.

 

[Torment]

Yeah, the Black stuff, is the Bead Sealant wich I will apply around the rim; will apply it around the base of the valve stem too.

I'm still a little unsure as to whether the pitting is the cause of the bead leak, as the inner side/upright of the bead is perfectly smooth and the flat of the bead also looks ok.

 

[ford46guy]

Yeah, the Black stuff, is the Bead Sealant wich I will apply around the rim; will apply it around the base of the valve stem too.

I'm still a little unsure as to whether the pitting is the cause of the bead leak, as the inner side/upright of the bead is perfectly smooth and the flat of the bead also looks ok.

The tire guy told me that is not really a sealing surface. Only what is close to the bead edge of the tire. Could be corrosion or just "sandblasting" from driving and dirt getting in there. Once salt gets in there it may stay trapped for a long period.

 

[Torment]

From a tyre filters perspective; how is bead sealer meant to be applied ?

As far as I'm aware; initially, it's meant to be applied to the bead of the tyre, not the rim, although it can be applied to both the rim and the tyre if wheel corrosion is present.

So, is it applied after the tyre has been mounted ?

Will tyre soap/paste/lube affect it's effectivness ?

In a tyre shop; once applied, it cant be expecting to dry before a tyre is fitted, it'll take too long, same whether applied to the rim.

Surely, there's got to be a better method of applying this stuff to the tyre or rim without making such a mess.

 

[eljefino]

Bead sealer is technically referred to as "vulcanizing compound." Not knowing exactly what it is, I suspect it chemically makes the bead softer so it deforms better. It also glues the tire to the rim and fills small rim imperfections.

 

[Torment]

Yeah, I know what it is, used it for years but not that often and it always makes a mess and is difficult to apply.

I've always applied it with tyre remaining on the rim but I can't imagine a tyre shop applying it before mounting the tyre, whether on the tyre, rim or on both.

It's not slippery enough to use as a mounting paste/lube and it takes far too long to dry; also, I assume to achieve an effective seal, the tyre has to be mounted whilst the bead sealant is still sticky.

I don't think there's a chemical reaction to make the tyre softer; surely, it just provides a seal and fills voids where the air can escape.

 

[Torment]

Update.... The 3 rims/wheesl/tyres, which I cleaned, flatted the bead, fitted new valves and resealed with bead sealer, have all maintained air pressure..... No bead or valve leaks present.