Four Common Questions About Tyre Pressure, Answered

Video: You probably already know that tyre pressure is important when it comes to safe driving, but it can also cost you money if you don't keep an eye on it. This video lays out the tyre pressure essentials you need to know. In this video from the Engineering Explained YouTube channel, Jason Fenske explains how temperature affects your tyre pressure, how tyre pressure affects your tyres' grip, how under-inflated tyres are costing you more money and how improperly inflated tyres will wear down much faster. For example, using the ideal gas law, you can assume that tyre pressure goes down 1 PSI when the ambient temperature goes down 5C. If the temperature increases, so does the tire's PSI. This can be dangerous in the winter time because you could be driving on under-inflated tyres if you haven't checked them since the summer. When it comes to tyre grip, low pressure in your tyres can give you more of it on a warm, dry day. If you're driving on a wet surface, however, low tyre pressure significantly increases your chances of hydroplaning.

If you want to keep your car's fuel economy at its peak, Fenske explains that it's best to avoid driving on under-inflated tyres. Less tyre pressure means more rolling resistance, and that means more energy is required to keep your cruising. Lastly, improper tyre pressure can cause tyres to wear faster than normal and greatly reduce their life. An over-inflated tyre will have more wear in the centre of the tyre, and an under-inflated tyre will have more wear on the outsides of the tyre. The bottom line is that you should always be checking your tyre pressure and adjusting it to the manufacturer's recommended levels — not just for your safety, but also to save you money in the long run.

4 Reasons You Should Monitor Tire Pressure [YouTube]


    And don't fall for the 'Fill-your-tyres-with-Nitrogen' con that many tyre dealers are pedalling.

      Really? Why not? It works - simply because the nitrogen molecule is larger than the normal air molecule which means it can't leak through the tire-wall so easily. It also doesn't expand and contract like normal air does, so your tire pressures stay pretty much constant regardless of temperature or season.

      I have been using nitrogen in my tires for many years, and only ever have to top them up once every 6 months.

        Oh dear. You do realise that air is 78 % nitrogen, yes? Do you really think that there's going to be a difference?

          I don't have an opinion on the efficaccy of nitrogen, but clogs makes a terrible argument.

          Letting 22% of the air out of a tyre is extremely noticable, so if smaller molecules really did leak significantly faster, nitrogen would make a significant difference.


            Thankfully there's only a 2.9% difference in size between molecules of Oxygen and Nitrogen ...

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