Does Temperature Affect Tire Pressure?
Many contractors do routine inspections of their industrial tires and equipment before sending them off to a jobsite. In a recent article, we listed six routine inspections that need to be done when preparing industrial tires for a jobsite and one of the more important inspections was checking the tire pressure.
However, did you know that the temperature can affect the pressure inside the tire?
To explain how this works, we need to refer back to the basic concepts of physics. The following statements show the relationship between gas and temperature:
- The volume of gas will expand as the temperature increases.
- The volume of gas will contract as the temperature decreases.
So how does this relate to the air pressure of your industrial tires?
Since the majority of job sites are outside the outside temperature is going to affect the air pressure that is inside of your tires. In addition to the outside weather temperatures, the tires themselves when in motion generate heat. Tires were created with two main functions in mind, to hold the air and to provide traction.
Two Tire Functions Affected by Air Pressure
#1. Containing the Air
The first function is that the industrial tire (or any tire for that matter) is a container of air which provides the support for the weight distributed on top of the tire. In other words, it’s not so much the strength of the tire material that provides this weight support, but rather the volume of air inside the tire.
Thus, it is very important to consider the temperature outside and the internal heat that is generated when your tires are in motion because for every 10 degrees of increased temperature your tires can be expected to increase 1-2 pounds. The same rule applies to a decrease in temperature but with a decrease of 1-2 pounds.
These changes in air pressure can be bad for your industrial tires because either they are now over-inflated and could blow out or they will become under-inflated causing less support for the weight that is pushing down on the tire.
#2. Traction on the Jobsite
Also, consider a second function and how it relates to air pressure. The tire is designed with tread patterns to offer the proper traction for job site surface conditions.
Proper air pressure provides proper surface area contact when a tread-patch-area of the tire comes in contact with the construction site surface or road at any given moment during tire rotation.
When heat causes the air pressure inside the tire to expand—that tread-patch-contact-area will become smaller—decreases—as the tire becomes over-inflated. This results in reduced traction, and ultimately affecting job performance along with uneven wear on the tires.
Conversely, colder temperatures will cause the tire to contract. With less air pressure to support the weight, the tread-patch-contact-area becomes larger—increases—as the tire becomes under-inflated (from weight pushing down on the tire).
The tread-patch-contact-area spreads out more flatly on the job site surface or road. This spreading increases resistance as the tires rotates across the job site surfaces and ultimately contribute to reduced efficiency, increased fuel consumption, sidewall tire damage, and overall reduced life span of the tires and treads to name a few of the associated problems.
Significant Temperature Fluctuations
When there are significant temperature fluctuations, contractors and machine operators play a significant role in helping to maintain the correct inflation pressure. It's best practices to consistently check your tire pressure and adjust it to the proper manufacturer specifications while keeping the current temperature into consideration.
Storing your heavy equipment outside exposes it to certain temperature fluctuations. For example, the difference between cold nighttime temperatures and daytime temperatures is about 20 degrees Fahrenheit. Assuming you have stored your heavy equipment
This means if you check your air pressure first thing in the morning and you check it again in the afternoon, the tire pressure will be about 2 psi higher.
In addition to this if you parked your equipment in the sun the radiant heat from the sun will temporarily increase the tire pressure.
Keep in mind that the tire’s maximum inflation pressure may be different than the tire pressure used to rate the tire’s maximum load. The tire’s maximum inflation pressure is typically branded near the tire’s bead and is the highest “cold” inflation pressure that the tire is designed to contain.
Since it is normal to have mild fluctuations when the sun heats temperatures in the day as well as extensive driving of the equipment, it is NOT recommended to reduce the tire pressure during mild increases as the pressure will return to normal levels once the industrial tires return to “cold” (or inactive) conditions.
Even though you may do your due diligence on making sure your heavy equipment tires have the correct tire pressure, it can be easy to forget that temperature can fluctuate and cause that air pressure to expand or decrease. It's best practices in environments where the weather fluctuations are more significant to measure the tire pressure a few times throughout the day.
However, it's not necessary to reduce the tire pressure if it increases a little bit during mild increases in temperature as the pressure will resume to normal levels once the tires are cold again.
For more in-depth information, consult a tire specialist at Monster Tires. We are your nationwide leader in industrial tires and industrial tracks. If you have any questions, feel free to give us a call anytime at 530.292.6400