I have just fitted a new Xtrons double din head unit that has facility for remote tyre pressure monitoring so I bought the kit that uses new valves that fit in the tyres. I've just been to a tyre place to have them fitted and they don't fit porsche wheels has anybody been down this road are there any available I didn't really want to use the big valve caps like most online systems and I am not sure even if my head unit will work with that type?