Inspect tires before long trips this spring

Harsh winter weather can negatively affect the performance of heavy-duty vehicles and could be the culprit for loss of tire inflation pressure (PSI) and decreased fuel mileage. Proactive tire maintenance could help prevent truckers from missing deadlines due to problems resulting from under-inflated tires. Here’s what truckers need to know about temperature changes and tire PSI as spring approaches.

Changes in air temperature affect the speed of air molecules in a tire, causing the PSI to fluctuate. This means that a truck starting its long-haul trip in Florida may notice a drastic change in PSI by the time it reaches its destination in Colorado. Hot tires can affect tire sound, in addition to pressure. Tires going off the highway may see a 15% increase in inflation pressure compared to cold tires. Cold inflation is based on an ambient temperature of 68 degrees Fahrenheit and does not include inflation pressure buildup due to vehicle operation.

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Drivers will not be able to determine the exact tire pressure rating just by looking at them. Therefore, it is important to recognize common symptoms of under-inflation, including: the TPMS warning light coming on on the dashboards; reduced steering and maneuverability; longer stopping distance; increased road vibration; and pounding noises from the tires. If any of these sound familiar, it’s probably time to pump up the tires to avoid trouble down the road.

Driving with under-inflated tires

You might be wondering what will happen if you ride with underinflated tires. Running a tire below the recommended PSI can reduce tread life and result in a substantial reduction in fuel economy. When tires are underinflated, the rubber-to-ground ratio is disabled and leads to increased friction. In turn, it causes overheating and premature tire wear (even a puncture).

The U.S. Department of Transportation has mandatory minimum tread depth requirements on all commercial vehicles, 4/32-in. for steer tire position and 2/32-in. in all other positions to ensure commercial truck tires have the proper tread level for operation. Due to these DOT requirements, truckers will want to inspect tires for the correct PSI and tire tread before making deliveries and pickups.

See also: Understanding the Tire/Energy Efficiency Equation

Explore the numbers

The PSI is a unit of measurement that is debated within the trucking community. When looking at the right amount of PSI for inflation, the consensus is that the PSI in heavy-duty applications will be based on several factors, including the maximum load capacity of each vehicle. Other factors include whether the trucks use “steering” or “driving” tires; tire brand; and tire size.

There is a maximum cold inflation pressure stamped on the wheel rims which should not be ignored. It is usually set at 120, 130 or 140 PSI. In most cases, the steer tire pressure can be set at 110 PSI while the drive tire pressure can be around 85 PSI. Tire inflation can be measured using a universal tire pressure gauge, such as a stick gauge. This type of tire pressure gauge has an accuracy rating of 3 PSI plus or minus and can be checked for accuracy using a master gauge.

To use a pressure gauge, drivers will simply remove the valve cap from each tire and place the pressure gauge on the valve stem. Then press hard enough to hear a hissing sound that will tell them the amount of PSI for each tire. If the tires are set below 85-110 PSI, it’s time to inflate.

The jury is still out on the perfect PSI numbers; but one thing is for sure, the weather outside can affect tire pressure and the number of trips to the gas station you make to fill up. As spring approaches, be sure to pre-inspect tires for proper tire pressure levels based on the application and other factors, including maximum load capacity and tire size. With these tips, drivers can hit the road without worrying about flat tires and missing deadlines.


Jennifer Smith is an eCommerce Digital Content Specialist for JAT truck parts.