Tyres slow leak

Jack up car and remove wheel Inflate tyre to 30psi Place tyre in bath and add water to cover as much of the tyre as possible Watch tyre and note where the bubbles are coming from. Buy tyre fitting machine and remove tyre Repair leak Buy Balancing machine and balance tyre Refit wheel to car and let the jack down.

Or just drive to a tyre fitting company and let them sort it out.

Or could it be that you ran over some sharp stuff with both rear tyres? Either way, go get them fixed, 10psi is dangerously low.

Only if you drive on them :-)

Alloy wheels do corrode inside, where the bead seats. This can often cause a slow leak. Too often tyre fitters are in too much of a hurry to clean it off, and just dump the new tyre on top of it. The only way to be sure is a bath of water, or you can use soapy water poured on. You will see the bubbles forming where the leak is. Try some on the valve head too in case it is that. If it is the bead, the only option is to take tyre off, clean the rim very carefully, and replace tyre.

Alt Beer brought next idea :

The alloy rim where the tyre seats is a notorious cause of air leaks. Just take the wheels off, lay them flat and level on their sides then pour some water along the grooves between tyre and rim. See if any air bubbles form. The fix is to have them removed, clean up the rims and reseat the tyre.

What they all said.

I had the same thing on one of my Mazda alloys - a very slow leak over several weeks.

After having the tyre taken off, the rim cleaned up (and a bit of goo slapped on for luck) and refitting, it's been fine for a year or more now.

Same on our Zafira (Sold Today) it was some corrosion on the rear wheels, tyre place took the tyres off cleaned the rim with a wire brush on an airtool, loads of "goo" and all's been well for 18 months, tyres are none the worse in that time either!! mitchelin energy's

PCPaul explained :

I did once hear of a batch of alloys which turned out to be slightly porous, allowing air out via the actual wheel.

It also helps to spray the (inside of) the rims with a suitably coloured paint after cleaning them or they'll just start corroding again.

Yes, I understand you are allowed to use your nearside rear wheel for a leak if caught short, but try not to make it too slow :-)

If I could get the tyre off the rim I could wire brush it, clean the tyre and put some goo on it. If I deflate the tyre, how easy it would be to get the tyre (P6000) off the rim and back on again after cleaning it up using ordinary home workshop tools?

If I marked the tyre and rim so that I could put the tyre back in the same place on the rim presumably the balance would still be satisfactory?

Thanks

Alt Beer ("Alt Beer" ) gurgled happily, sounding much like they were saying:

Bloody difficult to impossible.

...assuming you'd not in any way changed the position of any weight on the rim by, for example, cleaning off any corrosion and painting any bare bits of alloy...

For the sake of a tenner, take 'em down your local small backstreet tyre place.

...and very likely to damage the rim far beyond the help of any wire brushing or goop.

Ditto.

Do not try, you will damage something beyond repair.

Absolutely. I have a manual tyre-changer that I use mainly to strip old rims for scrapping. The forces involved are so great, especially with low-profile tyres, that they would easily damage alloy wheels, so I don't even attempt them. That really is a job for a pro with the proper gear.