What PSI Should a Spare Tire Be? A Comprehensive Guide

A spare tire, also known as a donut tire, is a smaller and temporary replacement for a flat or damaged tire on a vehicle. The recommended tire pressure for a spare tire is typically lower than that of a regular tire, as spare tires are designed to be used for short distances and at slower speeds until a proper replacement can be installed.

Understanding Tire Pressure for Spare Tires

According to the NASA Technical Standard NASA-STD-3001, Volume 2, Revision C, the tire pressure for a spare tire should be specified by the program or project. However, as a general guideline, the recommended tire pressure for a spare tire is usually around 60 psi (pounds per square inch).

This is lower than the recommended tire pressure for a regular tire, which is typically around:

  • 30-35 psi for passenger cars
  • 50-65 psi for light trucks

It’s important to note that the tire pressure for a spare tire may vary depending on the make and model of the vehicle, as well as the specific specifications of the spare tire itself. Therefore, it’s always best to refer to the vehicle owner’s manual or the spare tire manufacturer’s instructions for the recommended tire pressure.

Factors Affecting Spare Tire Pressure

what psi should a spare tire be a comprehensive guide

Several factors can influence the recommended tire pressure for a spare tire, including:

  1. Vehicle Type and Size: The recommended tire pressure for a spare tire can vary depending on the size and weight of the vehicle. Larger and heavier vehicles may require a higher tire pressure for the spare tire to provide adequate support.

  2. Spare Tire Dimensions: The size and dimensions of the spare tire can also affect the recommended tire pressure. Smaller spare tires, such as donut tires, typically require a higher tire pressure compared to full-size spare tires.

  3. Driving Conditions: The intended use and driving conditions of the spare tire can also impact the recommended tire pressure. Spare tires used for longer distances or at higher speeds may require a higher tire pressure to maintain stability and performance.

  4. Manufacturer Recommendations: It’s crucial to always refer to the vehicle owner’s manual or the spare tire manufacturer’s instructions for the specific recommended tire pressure. Manufacturers may provide guidance based on their testing and engineering data.

Measuring and Adjusting Spare Tire Pressure

To ensure the proper tire pressure for your spare tire, follow these steps:

  1. Locate the spare tire and the tire pressure gauge.
  2. Remove the valve stem cap and place the tire pressure gauge on the valve stem.
  3. Check the reading on the tire pressure gauge and compare it to the recommended tire pressure for your spare tire.
  4. If the tire pressure is too low, use an air compressor or a portable tire inflator to add air until the desired tire pressure is reached.
  5. If the tire pressure is too high, release air from the tire using the valve stem until the desired tire pressure is achieved.
  6. Replace the valve stem cap and ensure the spare tire is properly secured in its storage location.

Maintaining Spare Tire Pressure

It’s important to regularly check and maintain the tire pressure of your spare tire, even if it’s not in use. Here are some tips for maintaining spare tire pressure:

  • Check the spare tire pressure at least once a month, or before any long road trips.
  • Ensure the spare tire is properly inflated to the recommended tire pressure before storing it.
  • If the spare tire is used, check the tire pressure again before returning it to the storage location.
  • Avoid overinflating or underinflating the spare tire, as this can lead to premature wear or potential safety issues.
  • If the spare tire is damaged or worn, replace it with a new one as soon as possible.

Conclusion

Maintaining the proper tire pressure for your spare tire is crucial for ensuring its safe and effective use. By following the recommended tire pressure guidelines, you can help ensure your spare tire is ready to perform when you need it most. Remember to always refer to your vehicle owner’s manual or the spare tire manufacturer’s instructions for the specific recommended tire pressure for your vehicle.

References

  1. NASA Technical Standard NASA-STD-3001, Volume 2, Revision C: https://www.nasa.gov/wp-content/uploads/2020/10/2022-04-08_nasa-std-3001_vol_2_rev_c_final.pdf
  2. Local Government Engineering Department Manual: http://oldweb.lged.gov.bd/UploadedDocument/UnitPublication/1/313/16-B.%20DPP-Manual-Part-2.pdf
  3. Beamex Blog for Calibration Professionals: https://blog.beamex.com