Big fan of mobile fitting services, I've used a couple, was really impressed with Event Tyres and can't rem the name of the other company, but also very good 
Interesting chatting to you the other day and you mentioned alloy wheel corrosion, was a real eye opener!
Apparently Jan was talking to a wheel specialist who claims one of the biggest problems with alloy wheel corrosion is the chemicals used by some hand car washing outfits. The chemicals can be pretty harsh, and if you have any stone chips, it can get between the alloy and the protective layer, lifting it and exposing it to road salt etc.
Would certainly explain why my 4 year old RR alloys are starting to corrode
Although the fix is to be less lazy and wash it myself 