Alloy porosity

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You can't use inner tubes with most tyres now, regardless of wheel type.

The inside of the tyre is not smooth enough, plus the tube shape isn't designed for the low profiles currently in vogue.

Chris

Reply to
Chris Whelan
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ISTR way back when I was a lad, that some Norton crankcases were found to be porous. They had to paint the inside with something-or-other to stop them leaking.

Reply to
Dan S. MacAbre

While I may actually agree with the gist of your argument how many tyres are repressurized a thousand or more times a minute.

G.Harman

Reply to
damduck-egg

With alloy engine parts, the holes/pores soon block with dirt/carbon particles. In any event any leakage is made up in the next fraction of a second. Which doesn't happen with wheels.

Reply to
harry

You have carbon/dirt in your cooling system? In which case something is porous.

No it doesn't. But I'd love to hear of a wheel which was genuinely porous, rather than just a poor seal between tyre and rim.

And somehow I doubt you've ever changed a tyre yourself.

Reply to
Dave Plowman (News)

An immigrant does it for him :)

Reply to
Mark

If my pistons lose 0.1% of the gas on every stroke I won't notice. They are typically running about 25 power strokes a second. If my tyre lost

0.1% of its contents every 25th of a second I think I'd notice...

Andy

Reply to
Vir Campestris

How about the cooling system often made of alloy these days. If that were porous, it wouldn't hold pressure.

Reply to
Dave Plowman (News)

The tubes of an alloy radiator are wrought and not cast. The process that makes the tubes compacts the alloy, distorts the crystal grain structure and removes (most) porosity.

Casting process can entrain gas and that results porosity. So cast blocks and heads can be porous but drawn tubes and rolled sheet won't be porous. In part the thicker walls of castings prevent porosity as all the holes have to line up and join up for it to leak.

Aero grade alloys for large cast structures (jet engine intercase) are vacuum melted to remove gas and vacuum cast. They can still suffer from strain induced porosity, where voids open up between the crystal grain. Unlike a crack that will go though a grain.

Reply to
Peter Hill

But loads of the rest of the engine, cast. Many engines these days have an alloy block and heads.

Reply to
Dave Plowman (News)

I have built cars from the ground up. How a bout you?

Reply to
harry

That I very much doubt.

Very well, thanks.

Reply to
Dave Plowman (News)

Can you see the corrosion if you take the tyre off. i.e. is it obvious to repair.

Reply to
Michael Chare

yes, but I would usually put detergent around the tyre first to confirm the leaking side/area.

Reply to
MrCheerful

I had mine resealed they just spun them on a jig then applied some magic to the milled surface and they were excellent afterwards. 20 quid.

Reply to
Weatherlawyer

I doubt that is the problem as the tryes need to be leaking to allow ingress.

Reply to
Weatherlawyer

They seem to use some form of sealer these days. I was having two new tyres fitted to the old car when the fitter took a phone call after applying it to one wheel. And was on the phone for ages. He didn't apply more, and that tyre leaked. The other OK. Had it re-done and it was fine.

Reply to
Dave Plowman (News)

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