I've never been charged fitting on top of purchasing a set when I've bought a from a shop. Would have liked it to be £30 off the cost off each tyre. The local tyre shop only charges £20 to fit a pair of tyres if loose. To me, it's telling me that a tyre shop that never charges fitting can charge now or why don't they just say That you can buy a set of tyres with up to £30 discount on the tyres.
Trust me I am a retired Doctor and lecturer at Oxford University of Structural and Mechanical/Electrical engineering. May the shaft be with you