If you’ve already been learning about taking your 4runner off-road, you’ve probably already heard the term “airing down” your tires. In this article, we’re going to discuss what it means, how much air to let out, and how the heck you fill them back up with air in the middle of nowhere.
Airing down the tires on your 4runner is a good idea whenever you take it off-road. It’ll provide a smoother ride, more traction, and less wear on your suspension. The amount of air you should let out depends greatly on the terrain you’ll be driving on but you shouldn’t run less than 10 PSI.
What does it mean to “air down” your tires?
First of all, let’s be clear – this doesn’t mean you should be driving around with flat tires. As a matter of fact, you shouldn’t run less than 10 PSI unless you’re using “Beadlock” wheels.
Beadlock wheels do exactly what it sounds like. They lock the bead of the tire to the rim using a ring that’s bolted onto the wheel. This keeps the tire from rotating on the wheel itself or even unmounting itself from the wheel.
So if you’re running regular wheels (and most people are), you’ll need to keep a certain amount of air in your tires in order to keep them mounted to the rim. This is typically at least half of the pressure that you would run on the street.
The benefits of airing down your tires
Many people choose to let some air out of their tires before going off-road and there are some great reasons to do so. They can be paired up into 2 categories: increased traction and decreased fatigue.
Perhaps the biggest benefit you get from airing your 4runner’s tires down is an increase in traction. Reducing the air pressure in your tires creates a larger contact patch with the ground. The sag in the sidewall will cause them to be a bit wider but it’s the extra length that actually helps the most.
Dropping your tire pressure also allows the sidewall of the tire to wrap itself around obstacles and edges. Compare it to a rock climber using their closed fists to climb vs wrapping their fingers around each rock.
Letting some air out of your tires will no doubt provide a smoother ride. If you’re going to be logging a lot of miles on washboard dirt roads, airing down your 4runner’s tires can be a game changer.
Having the fillings rattled out of your teeth as you drive down a rough road can be exhausting. It won’t take long before your body gets tired from bracing itself from the thousands of tiny impacts.
As long as you aren’t running a low profile tire, airing them down will allow the sidewalls to act as a cushion. Driving on pillows sounds pretty dang comfortable, doesn’t it?
You won’t be the only one noticing a decrease in fatigue. Your 4runner will thank you as well. Again, that extra cushion in your sidewalls will do some of the work that your suspension would otherwise be tasked with.
Every bump in the road must first go through your tires before your suspension even knows it’s there. By absorbing it with your tires, your suspension doesn’t have to work as hard.
How much pressure you should let out of your tires when off-roading
In most cases, airing down to 15-20 PSI is optimal but different terrain calls for different pressures. For example, you’ll want to run more pressure if you’re driving at a faster speed on dirt roads vs rock crawling or driving on the beach. Start by removing 10 PSI and see how it goes.
You won’t want to drop too much air pressure if you’re going to be driving at higher speeds. Not running enough air pressure can cause your tires to overheat and you can even run the risk of a blowout in the worst case.
If you’re unsure of whether your pressure is too low, pull over after a few minutes of driving and feel the sidewall of your tire. If it still feels cool, you can either continue on or drop the pressure more if you feel it’s needed.
Airing down your tires in deep snow or sand helps a lot. These are two scenarios where you’ll probably want to run the lowest pressure possible. This will help you to float on top of the surface rather than having the tires dig down (and possibly getting stuck).
How to air your tires down
There are a couple of options for dropping your 4runner’s tire pressure. You can do it the old-fashioned way by simply pushing the valve stem with a screwdriver or stick. You’ll have to keep stopping to check the pressure and adjust as necessary. This can be time consuming but it won’t cost you any money.
If you’re going to be airing down often, you might want to invest in a set of tire deflators like these ones from JT Brooks. You calibrate them to your desired tire pressure, connect them to your valve stems, and let them do their job. You can deflate 4 tires in a few minutes without any hassle.
How to air your tires back up on the road
This has always been my main concern with airing down my tires. How do you fill them back up before hitting the highway?
You might get lucky and be off-roading near a gas station with an air pump. Otherwise, you’ll need some type of air compressor – either a portable one or an onboard one. You can use your truck’s electrical system to power it and get your tires back to highway pressure, even in remote locations.
These ARB air compressors have been incredibly popular with 4runner owners who want to have an onboard air setup hooked up on their rig. This is also handy for things like running an air-locker in your differential, using air tools, and blowing up bike tires (or your favorite inflatable unicorn at the lake).
If you aren’t looking to install a system on your 4runner, a portable air compressor like this one from Viair will work just fine. You can plug it into your 12V power outlet and set it on the ground.
The cheaper compressors from the parts store will overheat easily and struggle to fill up a 33″ or larger tire. Make sure to spend the money on a decent one from a reputable company and it’ll do the trick.
Tim is the creator of Canadian Gearhead. His experience with auto detailing and working for Toyota shows through all of the articles posted here. He runs the Canadian Gearhead site and YouTube channel full-time now and currently owns a 2007 4runner, 2006 Tacoma, and 1991 MR2. Read more about Tim: