Do Not Use 32 PSI On Your Car Tyres - We Explain Why!
Having the right tyre pressure is critical to ensuring proper tyre health. Most people follow the ‘recommended tyre pressure’ provided by the vehicle manufacturer. This varies between vehicle models. 32 PSI is a widely used value. Many blindly trust it and set their tyre pressures accordingly. In this article, we explain why it isn’t ideal to rely solely on manufacturer-provided numbers and how doing so can even lead to premature tyre wear.
On most cars, the recommended tyre pressure is mentioned on a sticker inside the front door jamb. It lists the suggested pressures for all four tyres. These values can be 32, 33, 35 PSI, or more, depending on the vehicle. However, this is not necessarily the ‘optimal’ tyre pressure.
These typically indicate the minimum pressure required to safely support a fully-loaded car (in the case of a five seater, five adults and a trunk full of luggage) travelling at 120 kph in hot conditions. Clearly, this is not an everyday scenario.
Most of us drive alone or with a single passenger. The boot is rarely fully loaded, and speeds are usually much lower. In such cases, running the recommended pressure can effectively result in under-inflation.
When you run the recommended pressure ( in this case, 32 PSI) in a lightly-loaded car, the side walls flex more than they should. The tyre loses its shape and the contact patch spreads beyond recommended levels. Eventually, the centre of the tread may lift slightly off the road. The vehicle weight will get concentrated on the outer edges. This leads to uneven wear, with the edges wearing out faster than the centre.
In reality, the ideal pressure to use on a given vehicle, depends on the tyres that it is running on, and not the vehicle itself. To find it out, check the tyre’s sidewall. You’ll see ‘Max Press’ or ‘Maximum Pressure’ written on it, along with a value. For example, you may find ‘Max Press= 51PSI’ on some. This shows the maximum pressure that the particular tyre has been engineered to handle.
To achieve even wear, sharp handling and maximum fuel efficiency, the ideal tyre pressure to use would be 10-15 percent lower than the maximum pressure mentioned on the side wall. In this case, it can be anywhere between 38PSI and 42 PSI.
No, using these pressures will not blow your tyres! Using 40 PSI on a 51 PSI-rated tyre is not even inflating it to 80 percent of its actual rated capacity. You are not over-inflating it, but actually taking it closer to the region where it was originally engineered to perform. Doing this will ensure even wear and significantly longer tyre life than otherwise.
As one last reminder, using the incorrect tyre pressure can lead to longer braking distances, sluggish steering, and an increased risk of blowouts. Prolonged usage on under-inflated tyres can also damage the car’s suspension, repairs and replacements of which can be expensive.
One should make it a habit to check tyre pressure periodically. This should be done when the tyres are ‘cold’- driven less than 1.6 km or parked for at least 3 hours. This will give the most accurate reading.
One should not trust the TPMS (Tyre Pressure Monitoring System) blindly. While it can be used to get near-accurate readings of tyre pressures, do not wait for the ‘warning light’ to inflate or fix a tyre that’s having an indicated lower pressure.
The warning lamps on most cars light up only when pressure drops 25% below the manufacturer’s recommended levels. In a case where the recommended pressure is 32 PSI, the light will only come up when the pressure drops below 24PSI. By that time, the side walls would be flexing severely and there would be higher chances of a blowout.
Tyre pressure also varies with outside temperatures. If you notice a sharp drop in tyre pressure during winter, it may not always be a leak, but simple physics. In such cases, check your tyre pressure more frequently and inflate if needed.
All in all, having the correct tyre pressure is critical in ensuring tyre health and safety of the vehicle. It is also critical in achieving optimum fuel efficiency and braking performance.