I want to fit lower profile tyres to my car because I’m changing my alloy wheels from 15in to 17in - how can I find the right size?

Our Tyre Size Convertor can help you out here. When fitting a different sized tyre, you need the overall diameter to remain the same - simply look up your standard tyre size on our easy-to-use convertor, and it will list the various sizes you can swap to. However, always check that a wider than standard tyre will fit inside your wheelarches - the only surefire way to do this is to get a tyre fitted to a wheel and try them back and front to ensure they don’t catch on the wheelarches, inner wings, or suspension components.

I’m fitting low-profile tyres to my car - what should the tyre pressures be?

That depends on what profile you are fitting, but generally the pressures will be higher than those for your standard-fit tyres. As the profile of a tyre gets lower, so does its Load Index - the amount of weight it can support - and that can mean as much as 100kg difference between the standard tyre and an aftermarket fitment. In extreme circumstances this might result in a set of low-profile tyres being unable to sustain the weight of a fully-laden car; this is illegal and dangerous, and will also damage your tyres.

Is there anything else I need to know about fitting lower profile tyres?

There certainly is. Ideally the load capacity of the low profile tyre should match that of the original, otherwise it could overheat, causing bad and uneven tyre wear, and potentially even a blow-out.

I’ve been told mixing and matching my tyres is a bad thing - is that true?

Certainly is. Different types of tyre behave in different ways, and in extreme circumstances that can upset the handling of your car. Different tread depths from side to side is also a bad idea.