With regard to the insurance side of things, I saw this on WatchDog (BBC) not so long ago. You do have to inform your insurer (though it would never have occurred to me) as it is technically a modification. However, the insurance regulator said it was out of order for individual insurers to increase their premiums because of a safety minded mod. So, if it should raise your premium, the advice was to complain in the first instance and follow the industry procedure for complaining all the way to the top. From what I understand the big names were the worst offenders and should have had their wrists slapped by now. Having said that, my premium has gone up by over £100 (25%) this year and is still the lowest price I can find (despite NO policy alterations/claims/etc), so I imagine they're just putting all premiums up to garner a bit more dosh from defending themselves in this case. However, if they find you driving about in your winter tyres in June, I guess they'd have cause to invalidate the premium entirely. :blink: EDIT: Just another thought, would you be insured at all driving on a combination of tyres? Two winter and two all weather I mean - that might cause problems with insurance. I imagine they'd want an all or nothing situation.