On Monday, 2 October 2017 11:37:37 UTC+1, wrote:
On Mon, 2 Oct 2017 11:28:06 +0100, "Dan S. MacAbre"
wrote:



Just the usual meja ********. If alloy really did go porous, your engine
would soon be scrap. Given pistons are made of alloy and have been for
many a year as is much else on a modern engine. And the pressure inside a
cylinder is far higher than in a tyre.

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

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.