Has anyone had problems with their tyres losing pressure? I have a 1999 2 ltr SE Exec with original 15" Honda alloys, and all 4 tyres are losing between 4 and 8psi per week. Seeing as all 4 tyres are losing pressure, could it be that the alloys have become porous? If so, would sealing compound help/cure this? I am also looking at replacing the front tyres. The spare wheel has an unused Pirelli, so was thinking of getting a matching one to save money. What brand do you recommend and what are the benefits of using that brand? Any help would be much appreciated.