Possible Clues:

• Political type helps to form sporadic alliances
• Revolutionary sort of tyre that's about to be introduced
• "Far out!"
• Moving away from the centre, Conservative held to be leftist?
• Revolutionary artist left caustic material for retrospective
• Progressive — car dial (anag)
• Extremist spoke about onset of change
• Revolutionary sort of tyre keeping cold
• Reformer
• Extreme cold getting into kind of tyre