Don't shoot me for saying this but those white wall tyre 'flaps' are a waste of time and money in my experience 😞 .
As has already been pointed out , they need to have red rubber grease (has to be this as ordinary grease will damage the tyres) regularly applied to the underside of the trim to stop friction between the tyre sidewall and whitewall insert.....
Without this grease, as the tyre rotates the whitwall insert will rub away at the tyre sidewall, with obvious safety consequences!
Many years ago I had a set on my daily driver Beetle, and despite regular greasing within a relatively short time the whitewall trims had almost totally worn away the words 'Firestone' from the tyre sidewall :shock: .
I promptly had the whitewall trims removed and wouldn't dream of recommending them to anyone, honestly :lol: .
Am sure there must be some people who have had white wall trims without any problems, but I have yet to meet one............. :lol:
'63 Karmann Ghia RHD
'72 1302LS Karmann Cabrio RHD