You have your wheels and you want to put your own personal stamp on them – great news. But, before you get your tool kit and decals out, it’s worth speaking to your insurance company.

Anything that is not part of the original model specification might be considered a modification or upgrade and therefore could affect your insurance premium.

So, if you fancy adding some alloy wheels, a spoiler or extra headlights, or even want to upgrade the brakes – it pays to do your homework first. Even some decorative extras could count.

The advice from the Association of British Insurers is clear: what constitutes a modification is different for each insurer so make sure you at least have a conversation with your broker before you start any work, just in case you decide it’s not worth the hassle.

A spokesman for ABI told us: “The insurer would want to know about modifications that change the risk of you damaging the vehicle or having an accident. They would also want to know if you modify your vehicle and make it more expensive to repair if you were to have an accident, or more likely to be stolen or vandalised, i.e. new expensive tyres, bumpers, etc.”

The insurer would want to know about modifications that change the risk of you damaging the vehicle or having an accident, make it more expensive to repair, or more likely to be stolen or vandalised.

This is because when your insurance company arranges a policy, it has to take a number of considerations into account. These include the value of the vehicle, risk of theft and the risk of being involved in an accident. It’s why policies vary from person to person quite significantly.

Modifying your vehicle can have an impact on all of these elements: it might make it more attractive to car thieves or your accident risk might increase if you have souped-up the engine. These so-called aftermarket changes can also increase the value of the vehicle.

If you take the risk of not informing your insurance company and you are subsequently involved in an accident or your vehicle is stolen, you could find your policy is void.

It’s also worth making the point that you should inform your insurance company about any vehicle that you buy that already has modifications – whether that car is second hand or new.

There is some good news, though: most insurers do not add a premium for winter tyres, provided they are roadworthy, and if you add a recognised security device to your vehicle you could see your premium actually go down.

Have you ever come unstuck for not declaring modifications to your car? Let us know on our Facebook page.