Assuming your tyres have the required legal tread depth and have no damage or wear that would cause them to fail an MoT, there is no reason that tyres of this age would cause your insurance to be invalidated. However, it is always worth bearing in mind that in the event of a claim an insurance company may examine your vehicle for anything that could be judged as unsafe or not in accordance with the manufacturer's specifications. It is generally accepted that assuming there are no other faults or signs of wear tyres should be replaced when ten years old regardless of condition.