Got a persistent leak, about 10psi per week, from 225 55 R17 Goodyear on an MB alloy wheel. Tyre is getting on a bit but not at fault. Had it before and the tyre was taken off and the wheel rims cleaned and a sealer put on. That cured it but now it is back. What's the solution? Would having the wheel completely refurbished to the job? Have just read that the worst case is that the wheel cannot be saved. That true?