You know what guys? I have to thank you lots for this; I was going to get alloys and didn't know at all that I had to inform the insurer, I thought it was only for "performance" mods.
16" (same size) alloys will add £350 on to my insurance; which is me not getting alloys! Maybe next year when I have 1yrs no claims and I'm 25 (and no, I'm not accident prone - I've only been driving a year)
Only to happy to help.
Many people make the mistake of changing their cars from manufacturers specs and don't inform their insurers. It can be a very expensive mistake as you are in reality not insured. This makes you liable for prosecution for not having insurance and liable for all the costs if you do have an accident or loss.
Insurers will always ask the question "Have you modified the vehicle" and you must always say yes if you have changed anything. Even upgrading the HiFi to a non standard spec can be seen as an increased risk by the insurer. And if it is an increased risk and you did not inform them, you are not covered.
The reason behind all this is the 'risk' being taken on by the insurer.
They know the risk for the standard car, but as soon as anything is changed the risk also changes and therefore the insurance premium due.
Also the cost of the vehicle is different with the added items, something that should also be stated in its value when asked.
If you have a £15,000 car and you add £5,000 of extras then if you don't declare the value as £20,000 they can invalidate your insurance (saying that you tried to get a cheaper premium by underestimating the cars value) OR they will limit any claim to the value insured. Meaning if the car was stolen and not recovered you would only get a maximum of £15,000 and lose the £5,000 of extras.