You see them on every corner of the Internet, articles telling you how to save fuel with lower tyre pressures. But are they true? Are lower tyre pressures perfect for your car? We’ll summarize what you should know about it.
Let’s start by saying that everyone is free to do whatever they want on their cars, but if someone wants to mislead other people into making false claims about something, then we have a problem. Just because things are always done in a certain way does not make it the best approach, and we’re going to tell you why.
Low Tyre Pressure = Hard Tyres?
One of the most repeated claims by low-pressure advocates is that lowering air pressure will make tyres harder, increasing your grip. This is entirely false. Hard tyres do not equal better grip; if anything, they are dangerous.
Why? More complex materials deform less, so at best, all you’ll get is harder rubber touching the ground – but this would only create more rolling resistance, not more grip. Deformable or soft fabrics are required to have meaningful amounts of grip. Suppose Tyres Hounslow pressures were increased just enough to compensate for the extra load caused by lower air pressure (the total tyre contact patch area remained constant).
In that case, you’d be making surface contact with vastly hardened rubber, which would cause much higher rolling resistance and less grip than “hard” Hounslow at the proper pressure. So forget about “hardness”; it has nothing to do with grip.
This simple truth has been known for a century, and it’s why the valve stems on your everyday car tyres are not pressurized – so if you’d like to experiment with tyre pressure to see what we mean, feel free to remove the valves from any of these:
When people tell you they went faster around corners by lowering their tyre pressures to ridiculous “warm weather” levels, this is likely just due to increased rolling resistance, which can be caused by many other things than air pressure such as wheel balance etc. It doesn’t matter whether rolling resistance was increased by lower tyre pressure, increased weight or increased torque – higher rolling resistance means slower acceleration and worse fuel economy, but it will never cause better grip.
You Want Lower Tyre Pressures in The Winter.
Well, actually, no. Winter tyres have a much larger contact patch, so their adequate pressure can be quite a bit lower than summer tyres. Still, it doesn’t work the other way around – you should never expect to gain any meaningful advantage by lowering your summer tyre pressures into the winter range. If you could pull that off, you’d probably change from summer tyres to winter tyres at some point during the year, which would mean there’s no reason not to just leave them on all year round and benefit from even better grip throughout the whole year.
So Why Do People Tell You Otherwise?
It is mostly wishful thinking and misinformation. Lower air pressures make for the harsher ride because rubber deforms more when subjected to smaller forces, so tyre sidewalls will be pushed in more, and it’s this deformation is the actual cause of the harsher ride. That’s why we want soft tyres: because they deform less, not because we need more grip (which we don’t).
What About Fuel Economy?
This one is tricky: if you drive at lower speeds, then your car will require less energy to overcome road resistance and rolling friction, which means that your tyres won’t have to expand as much under load, resulting in lower pressure required for a given driving speed – but there are limits to how far you can take this since driving too slowly makes control difficult! The tradeoff with low pressures also reduces contact patch area and hence reduces grip.
But the main reason why tyre pressures are often blamed for poor fuel economy isn’t that they affect it, but rather because many people ignore the natural causes of poor fuel economy. Excessive weight typically reduces fuel economy by 20-30%, so if you’re carrying 200kg in your boot, this is probably the most significant factor contributing to reduced efficiency – not too much air pressure or too little.
Even worse may be driving habits – e.g. if you drive aggressively with low downforce, engine braking and high RPMs, then your car will hate it, and fuel consumption will inevitably suffer as well as your tyres wearing out sooner! It is entirely separate from how much rubber touches the ground, which is only one of several factors that determine how much your tyres will squirm and deform during a particular manoeuvre.
There’s also some truth to the idea that letting out some air pressure on rough surfaces can reduce rolling resistance which saves fuel, but this isn’t too significant unless you drive on terrible roads all the time.
So please don’t blame tyre pressures for poor fuel economy – instead, check what you’re carrying in your car and learn to drive smoothly. The only reason why we want high tyre pressures is for better control.
Well, we indeed want our tyres to sit firmly on the ground and not leave any unsprung weight hanging about.
However:
This is more of an issue with bumped cars (e.g. lowered) since raising the car back to normal ride height without doing anything else to compensate for the change in geometry will make it sit lower and increase tyre pressures a bit. This is a desirable effect on race cars but not too good for everyday driving…
It’s also true that higher tyre pressure helps with reducing wear by increasing contact patch area, which reduces the force per unit area applied to each part of the Cheap Tyres London – but this is only an issue if you drive hard or on bad roads, so if you do then there’s no reason why you shouldn’t just choose your tyre pressures according to how much grip you need.
And while performance drivers often reduce tyre pressures slightly on track to get a more lateral grip at high speeds, this has nothing to do with saving fuel or reducing wear.
Why is it so Hard to Choose the Right Tyre Pressure?
The truth is that most tyres are actually overinflated for everyday use, so if you go slightly below what’s stamped on the sidewall, then they won’t feel too bad.
Remember that if your pressures are really low, this will come at a cost in terms of ride quality and tread life, not to mention the increased risk of punctures – but it can be worth it in terms of better grip when cornering. Don’t forget, though that is choosing the correct tyre pressures also depends on other factors such as weight distribution (e.g. if you carry lots of passengers/cargo), road conditions (e.g. on poor surfaces, lower pressures may be better) and suspension setup (the wrong springs or dampers can make tyre pressures too high or low).
