Hi.I posted this question earlier but it doesn't seem to have got through. I am having trouble with the pressures on three of the wheels on my car,both front and one rear. I regularly keep them pressed up to 28/30 psi but within 7 to 10 days the three aformentioned drop to about 20 psi. On advice I have changed the valva cores to no advail. Someone did mention that the alloy wheel rims could be porouse (wrong spelling?) any thoght please.
The air is obviously leaking from somewhere, could be porous alloys, the actual valve could be leaking around it's base, you might have small punctures though that is unlikely.
I don't know if you use Google as your search engine but if you do download their enhanced tool bar, it has a spell checker for anything you type in web forms like these, i use it to help with spelling.
i would as Zacmaster has said,try having them refitted to the alloys making sure the edges of the wheels are wire brushed down to get rid of any rust or crap on them,and have new valves fitted.