For W- speed rated Pirelli P-7R 275-55 x 15s, try contacting the Swedish Pantera Klub . They went in with the British Lamborghini owners group a few years ago and bought 200 tires from Pirelli's vintage tire-making plant in Turkey. Each club took half; this size fits Countache front wheels, Miura rears & Pantera/Mangusta 8" rear wheels. I have a pair on 8" Campys and they fit and handle well. The modern compound is not at all like the '70s P-7s. The W speed rating is for continuous speeds up to 168 mph.
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