Pirelli will trial prototype tyres at Spa

The Formula 1 drivers will all have two extra sets of tyres to run during Friday’s practices as Pirelli are testing a prototype tyre.
Pirelli have announced that the drivers will run the unmarked rubber during FP1 and FP2.
The tyres that will be tested have been modified to deal with “possible consequences generated by accidental multiple impacts on kerbs or other external bodies.”
Back to school in Spa. In Fp1 and Fp2 tomorrow we will test prototype unmarked tyres modified to even further (1/2) pic.twitter.com/qqnjbcFtwg
— Pirelli Motorsport (@pirellisport) August 25, 2016
… protect the tyre from possible consequences generated by accidental multiple impacts on kerbs or other external bodies (2/2)
— Pirelli Motorsport (@pirellisport) August 25, 2016