Run Flats and Insurance

[bd02]

I'm currently trying to get some runflats fitted to my Cooper... proving harder than I imagined as most local tyre dealers are refusing on the basis that it will invalidate my insurance. Now I know that they prefer to fit the run-flats due to the fatter margin but seems odd that they would flatly refuse to fit conventional tyres without good reason. So what's going on here?? Do insurance companies have a policy on this? anyone checked with their insurer before making the switch?

Thanks

[bd02]

Sorry - what I meant was that I'm trying to get some NON runflats fitted. I have spoken to my insurance company and there is no issue at all. God these tyre places irritate me.