Few things are more important to the safety of your family and your truck than your tires. The trouble is, there is a lot of misinformation and complacency out there. Few people really know the proper tire pressures required and even fewer people check them on a regular basis. First a disclaimer. When it comes to tires, we’re no experts. We neither design nor sell tires for a living. But we do have a lifetime of experience, having owned over a dozen trucks, truck campers, and travel trailers, and having read numerous publications and articles on how to properly inflate and care for them. It’s hoped that this article will spark interest on tire safety and serve as a gentle reminder on the importance of proper inflation and periodic inspections. Note, that the information contained in this article deals primarily with tire pressures for driving on pavement. Look for another article soon on airing down your tires for off-road travel.
Without a doubt, improper inflation is the greatest cause of tire failure. Indeed, driving on an over or under inflated tire is dangerous and can lead to a tire overheating and bursting. Overheating is a very bad thing for tires, but it’s even worse when carrying a heavy load like a truck camper. If you’ve ever suffered a blowout you know how dangerous and difficult it can be maintaining control of the vehicle at highway speeds. Not only that, but an over or under inflated tire can experience excessive tread wear thus leading to the reduced life of the tire. An under inflated tire can also increase the rolling resistance of the tire and can lead to reduced fuel economy. With the price of fuel being what it is today, every mile counts, especially when hauling a truck camper. Some owners like to over-inflate their tires to decrease rolling resistance, but the benefit of better fuel economy is offset by the greater risk of suffering a major blowout (not to mention a rougher ride). It simply isn’t worth the extra risk.
There are two basic approaches you can take on proper tire inflation. The first is to use the inflation values recommended by your truck manufacturer. These values can be found either on a placard located on the driver’s side door pillar or in your truck’s owner’s manual. The placard for our Ram 3500 calls for the front Firestone 275/70R18E tires to be inflated to 60 psi and the rear tires to 80 psi. It’s important to understand that the inflation values on the placard assume a maximum payload, which is why 80 psi is required for the rear tires.
The second approach to tire inflation varies both the front and rear pressures based upon the combined weight of your truck and truck camper. For this approach, you’ll need to take your truck and truck camper to the scales to get weighed then refer to your tire manufacturer’s tire inflation chart and inflate accordingly. The Firestone tire inflation chart for Medium Truck (MT) and Light Truck (LT) tires can be viewed by clicking here. When using these tables remember to multiply the listed values by two if you’re going by the actual weights for each axle of your truck.
Which approach is best? The Tire Industry Association’s website recommends the first though the second works well, too. Which do we actually prefer? We prefer the first approach since our truck camper comes close to maxing our truck’s payload rating, though when unloaded we do like to air down our rear tires to 45 psi, so our ride is smoother and less harsh when going over bumps. And for those who are curious, if we were to use the second approach with our camper loaded, we would put 50 psi in the front tires and 70 psi in the rears.
As you can see, the differences between the two approaches are pretty minimal, so we prefer to go with the slightly higher inflation values strictly for the better fuel economy. The bottom line is that you can’t go wrong using either approach. They’re both right, though many feel more comfortable staying with the truck manufactures’ suggested inflation values.
There are a few things you need to keep in mind when checking your tires. First, always measure a tire’s pressure when it’s cold. What is a “cold” tire? It’s a tire that has been driven on less than one mile and a tire that hasn’t been sitting in the hot afternoon sun. This is important because driving at highway speeds in the heat of the afternoon sun can raise a tire’s pressure as much as 8 psi. Because of this we like to check and fill our tires first thing in the morning when it’s the coolest. When filling, never exceed the maximum psi value listed on the tire’s sidewall. Load Range E tires, those typically found on three-quarter and one-ton pickup trucks, have a maximum pressure of 80 psi. Oh, and when checking your tires, don’t forget to check the spare. This is a common mistake and one we’re guilty of forgetting to do from time-to-time.
The maximum tire pressure brings up a good point and another mistake commonly made by newbies. As we just discussed, a tire driven at high-speed can see an increase as much as 8 psi. For a Load Range E tire recently filled at the maximum pressure of 80 psi cold, this means you could see a reading as high as 88 psi immediately after returning from a road trip. This is nothing to be alarmed about. Tires are engineered to handle the extra heat and corresponding rise in pressure that driving at high-speed naturally causes. This extra “hot” tire pressure is perfectly normal and doesn’t need to be bled off. Doing so is a common mistake made my newbies. Don’t fall for it. Compensating may result in under-inflation. Besides, tire pressures are to be taken cold, remember? Not after returning from a long road trip.
How often should you check your tire pressures? We like to check ours before each outing and each time before we go to the fuel pump. It’s important to check your pressures regularly due to a process called permeation. Tires lose air normally through this process, but changes in temperature can affect the rate at which your tire loses air. This change is accelerated in hot weather though a tire can still lose one or two pounds of air per month during the winter. When checking your tires, make sure all of the valve stems are equipped with valve caps to keep out dirt and moisture. This is especially important if you like to drive off-road. Oh, and speaking of valve stems, always make sure that your LT tires are equipped with metal stems to handle the higher pressures. Believe it or not, some tire shops are guilty of making this mistake. We’ve had it happen to us on one occasion.
No doubt you’ve heard some good things about the use of nitrogen in tires. Proponents claim that nitrogen is denser than air and less prone to permeation thus enabling a tire to stay properly inflated longer. This, they say, leads to better fuel mileage and less wear and tear on your tires. Yes, the claim is true, but the cost for nitrogen–anywhere between $5 and $12 per tire–far outweighs any benefits derived from the gas. Now if it was free, we’d certainly use it, but it isn’t. In our opinion, nitrogen is just a scam, another way to fleece the public. Those who claim otherwise are usually those with a vested financial interest in the subject. Remember that.
Lastly, since we’re on the topic of tire care, it’s important for all truck and motorhome owners to carry both a tire repair kit, like the Safety Seal Pro Tire Repair Kit, and a portable air compressor, like the VIAIR 450P Portable 12 volt Air Compressor. Many RV owners, like us, like to boondock and travel far off the beaten path. Having these items with you gives peace of mind knowing you can repair a leak and air up your tires after a day on the trail. These items, of course, should be part of a well-stocked emergency roadside kit, a kit that every vehicle owner should own.
Is the 80 psi tire pressure with the camper loaded or unloaded on the truck?
Either, but the max 80 psi pressure provides the best load support, basically what the tire is rated for.