fitting or balancing

Just been quoted £20 to fit and balance two rear tyres for the runabout Civic by Honda dealer. Mytyres.co.uk can supply dunlop sp300 or bridgestone 391 for 40 quid per tyre. There is a dealer they list who fits/balances up 20 inch tyres for £5 per tyre inc. disposes of old tyre for 1.00 and...