I've seen a recent spate of threads across various forums and even articles on the news where insurance companies are charging people "extra" if they fit winter tyres as they regard this as a modification.
Me personally i wouldn't tell them i had them fitted if i knew they would charge extra. Now some might condone this as fraud, misleading etc however look at it this way:
Your car's tyres are a maintenance part. As the car doesn't have a specific OEM tyre then it can't be classed as a modification. A modification in terms of insurance is anything that deviates from from an OEM part to alter the cars ability be it in power, handling, braking, looks, desirability to thieves etc etc.
Now some insurances are saying that winter tyres are a modification as they encourage a driver to travel at higher speeds in adverse weather, therefore increasing the chance of an accident and hence a claim. However as all tyres have different characteristics are they going to start altering insurance premiums say for example if you replace you Vredestein Ultrac Sessantas with Michelin PS3. As i know from experience these 2 tyres have markedly different handling capabilities. What if you have 2 tyres of one make on one axle and 2 of another on the other axle?
We could take this even further. If you have your car serviced by 2 different dealers at some point and one uses a different make of Oil to the other do you have to declare this? What about brake pads? does this apply if you replace these again at 2 different dealers and they use 2 different makes? If you wash your car and then wax it using a different wax to what was put on at new does this again class as modification?
Now i am considering writing a letter, containing a petition, to the CII, who is the governing body, The ABI and the FSA and ask them to clarify why some insurance companies are allowed to charge more and some don't. I think it is absurd that fitting a better tyre for adverse weather is classed as a modification.
I think an insurance company would have an extremely hard time in court justifying not paying out.
Now i am not advising people to mislead their insurance companies. If you do so that is your own personal choice.
I am however looking at garnering support and if i get enough across a few forums i will set up an online petition which will run for one month before i send a letter. I will of course post up said letter and petition for all to read. In the mean time i would suggest shopping around if your not happy with your current insurer.