That's a decent deal. www.tyremen.co.uk does a set of 16-inch Alutec alloys for £335 inc, plus the tyres. But, of course, the total cost depends on which tyres you go for. You could fit excellent Goodyear Vector 4 Season tyres and leave them on all year round. You need to disclose the ‘modification’ to your insurer but there should be no penalty.