And you think this plastic ring will stay in place when installing a tyre? I highly doubt it chap, they are just to protect from kerbing. Come tyre fitting time, they will rip them off before the tyre, then you're back to sqaure one.
I beleive there is a list on the Pirelli site which lists their "pro delears" or something, some certification to say they can do big perfomance wheels and all use plastic fitments to stop you damaging the wheel. Best to use them or a trusted place. I use my local wheel refurber, its not an advertised service from them, but as they refurbed them last time, they take as much care as possible, and have never marked my wheels, and always come back perfectly balanced.