Slow leak in tyre. What are my options?

Question

When putting on the winter tyres, I noticed one had gone rather flat over the summer (1 bar, down from 2.5). I pumped it up go 2.5 and let it rest for week in my trunk, it was then down to 1.5 bar. Here's what I tried to find the leak:

• pump up to 2.5 bar again, put in bathtub (up to the rim) to look for bubbles, rotate slowly

• spray with soap-water mix (as described here), including valve and rim between tyre and wheel

• check if valve sits firmly, screwed it in about a quarter turn tighter.

I didn't find the leak. What should I do next to fix the tyre, or do again but differently?

Answer 1

If you can't find it readily as you state in your question, take it to a tire shop and have them re-seat the beads. This would not be completely dismounting it, but rather, take the beads off the rims, then clean around the mating surface, put some new mounting goop (soapy water or whatever they use), and re-seat the beads. If the valve stems aren't leaking and there's no puncture(s) in the tire itself, about the only other place it can be leaking is at the bead.

Answer 2

You never mentioned whether rims are steel or aluminum. Every aluminum rim is either painted (epoxy) or clear coated......against oxidation and corrosion. Bare aluminum oxidizes and if rims aren't painted or clear coated, inside and out, oxidation automatically begins right after manufacturing. New rims with new tires are fine until time passes and curb rash chips away paint/clear coat to allow oxidation. Oxidation around the bead seal simply allows corrosion to work its way between tire and inside the rim to create bead leaks. Discoloring from chipped paint or clear coat are signs of oxidation/corrosion that will work to create bead leaks. Steel rims are painted and can suffer the same corrosion but rust when paint scratches occur around the bead seal. Pressurize the leaking tire to around 40-50 psi then spray soapy water around the bead seal. If bubbles appear, remounting tires won't correct bead leaks. The tire should be dismounted and rim refinished to clear coat damaged areas, including sanding clean the inside of the rim and apply clear coat. This reseals aluminum against future oxidation and bead leaks.