To those of you who have fitted spacers, how do your insurers treat this type of modification? Do they just note it on the policy FOC or do they tend to charge an additional 'premium'?
I personally don't plan to inform them, rightly or wrongly.
Kalimon, you'll probably find in the wording of your insurance policy it is a requirement of your insurer that you notify them of any modifications to your vehicle, and fitting spacers is a modification as you're changing the factory build spec of your car. Technically, if you've not told them, they could invalidate your cover. Also, if you're unfortunate enough to need to claim, they could repudiate your claim. If you're with a mod-friendly insurer, chances are they'll just add a note to your policy without charge. Worse case scenario, your insurer might make a small charge, but for peace of mind you'd be better off telling them.
I told my insurer when I changed the alloys on my previous car. They asked me the value of the wheels, and needed confirmation that I had locking wheel bolts fitted. They merely noted my policy, and there was no additional charge.