Our experts on: Tyre pressures and new cars
You’ve all seen those car carriers barrelling along the highway, with seven to ten cars clinging precariously, so it seems, to the back of the prime mover-trailer combination. They move along, don’t they!
But what of the bright shiny near cars clinging on, sometimes at acute angles?
Look closely as you pass (if you can), and you will see that their wheels are clamped solidly to the ramps with wide webbing straps. Even though they may jiggle up and down on the trailer, there is not much “swing and sway” of the cars or R.V’s on the ramps.
This is because their tyres are inflated “hard”- around 42 psi – the so called “shipping pressure”. This stiffens the sidewalls of the tyres, and reduces lateral (sideways) movement of the car right up there on the ramps.
When the cars get to the dealership, they are unloaded and given a pre-delivery check – one of the extras that you pay for as part of the new car buyer’s deal.
One of the items on the list is “Check air pressure”. All that the car detailer has to do is make sure that the tyres have air in them. They may just look at them, and if they are not flat at the bottom, then that may be good enough.
The customer picks up his new car, and notices immediately that it is much harder riding, and a lot twitchier, than the demo ride he had before he signed up.
First step then is to check tyre pressure and reduce it to where it should be – the pressure specified on the tyre placard, which normally is either on the side of the driver’s side door, or on the door pillar.
There is a range of pressures specified there depending on the loads and speeds that the vehicle is going to be subjected to in service. So make a decision, based on your knowledge of how YOU are going to use the car, and drop the pressure to a normal range.
This will have two effects- it will give you a more comfortable ride, and make the car less sensitive to steering input- less twitchy. It will also jar the suspension less, and increase the resistance of the tyre to abuse such as hitting a sharp pothole at speed, which might (rarely) cause a blow-out.