After fitting whitewall tyres to my Coupé last year I asked around for suggestions for a suitable product to keep them clean. I was eventually directed to a company in Stamford who trade as "Race Glaze", and purchased a bottle of their whitewall tyre cleanser.
The results were very good, and I can recommend this to anyone else looking for a similar product.
I have also tried their "Crem Perfection" carnuba wax polish. This I can also recommend, it goes on with very little effort and buffs of to a superb shine without leaving any white residue on the car, the polishing cloth or me! Quite a welcome change after years of using Mer and Autoglym.
Race Glaze have a full range of cleaners and polishes and applicators, all of which can be found and ordered via their web site at : www.raceglaze.co.uk
Their delivery is first class too, items I ordered on Wednesday were delivered on Thursday am!
Usual disclaimers apply, my only connection to this company is as a satisfied customer.