What's psi for tires?

Looking at my truck tires, they indicate 50 psi cold, but the sticker on the door jamb recommends 35 psi cold. These numbers are significantly different! I use this truck for towing my 6000 lb trailer, and since my wife is into rock hounding, it’s often loaded with a few hundred pounds of rocks (I’ve calculated the number of buckets we can carry and we keep an eye on it).

So, what psi should I use?


The right amount of air for your tires depends on what your car needs. Usually, it’s between 28 and 36 pounds per square inch (PSI). The number written on the side of the tire might be higher, like 44 PSI or even 50-51 PSI for tires made for faster driving. Here are some examples of the recommended PSI for different types of cars and tire sizes:

  • Small Car with a regular tire size of about 185/55 – 15 should have around 30 PSI.
  • Medium Car with a regular tire size of about 195/55 – 16 should have about 36 PSI.
  • Large Car with a regular tire size of about 245/55 – 18 should have about 42 PSI.

The tire pressure indicated on the tires is usually the maximum pressure that the tire can safely handle when cold.


For towing and carrying heavy loads, it’s important to adjust your tire pressure accordingly to ensure safe handling, stability, and tire longevity.


However, exceeding the maximum pressure indicated on the tires is not recommended, as it can affect the tire’s performance and safety.

1 Like

You’re right; there’s a significant difference between the recommended pressure on your door jamb (35 psi) and the maximum pressure rating on the tire sidewall (50 psi). Here’s how to approach this for safe towing and hauling:

For Towing:

  1. Consult your truck’s owner’s manual: The towing section should specify the recommended tire pressure for towing a trailer. This pressure will likely be higher than the 35 psi on the door jamb for unloaded conditions.
  2. Don’t exceed the tire’s maximum pressure (50 psi): While the sidewall indicates 50 psi as the maximum safe pressure, it’s best not to inflate to the absolute limit, especially when towing. Aim for a pressure a few psi below the maximum, following the towing recommendations in your manual.

For Hauling Rocks:

  1. Consider the total weight: A few hundred pounds of rocks likely won’t require a significant increase in tire pressure from the unloaded recommendation (35 psi). However, if you’re consistently hauling a heavy load, consult your owner’s manual for recommendations on adjusting tire pressure for increased weight.
  2. Don’t overload your truck: The maximum weight your truck can safely carry, including passengers and cargo, is listed on the sticker on the door jamb. Stay within this limit to avoid tire and suspension problems.