What pressure to run off road?
It is important to remember that factory recommendation for tire pressure on Sprinter 2500 with oem tires is 49 psi front and 69 psi rear. As such, on a large heavy vehicle like the 4x4 Sprinter, you should never go below 18psi off road like you would with a dedicated lighter 4x4 vehicle who could go as low as 10psi. Remember that if you add weight such as a winch, bumper, etc on the front, it will affect front tire pressure recommendation as well.
Tire pressure obviously varies depending on tire type (load rating), vehicle weight and temperature. When driving at higher speed on asphalt, it is recommend to keep tire pressure at 40psi or higher, which will wear tires unevenly but maintain minimum safety. Driving at high speed with low pressure on asphalt will generate a lot of heat and compromise braking and turning speed.
A general rule is to deflate tires until 25% of sidewall is lowered and then record tire pressure for reference. I run E rated (10ply) BFG K02 tires on my Mercedes 144 Sprinter 2500 which is over 9,000 pounds when loaded. Here are my tire pressures for reference.
When off roading,
- on forest roads: 30psi Front / 35psi Rear
- on uneven trails and compact rocky terrain : 23 psi Front / 28 psi Rear
- on sand and deep snow: 18psi front and 23psi rear.
(ARB graph of tire footprint pressure for standard 4x4)
How to inflate tires quickly?
Ideally, the fastest way to inflate and deflate tires on Sprinter is to have a CTIS (Central Tire Inflation System) with an air compressor which enables you to inflate and deflate on the go from the inside of the cabin. However, such system is expensive, often require modified hubs, and is known to be unreliable. However, buying wheels with double valve stem abilities will allow you to install larger diameter stems such as the Apex R.I.V. for faster inflation.
The second fastest way to inflate tires is using a CO2 tank such as Powertank. They will enable you to inflate your tires (33-35") at least a dozen of times; unfortunately CO2 isn't as abundant when traveling and finding a place to refill the tank can be prohibitive.
The third and most common way to inflate tires quickly, is to use a powerful air compressor such as the ARB twinair whether in a portable or a permanently mounted with AO or VC mounting plate. Available with a single or double compressor, the dual compressor has 100% duty cycle, meaning that it can run continuously, and at 12v 4.68 CFM @29psi! A cheaper alternative would be the Viair Constant Duty, which can be doubled for increase speed (had Viair with 2gal tank for 5 years with no issues on my Tacoma). When comparing comparing air compressors, make sure to check CFM @ similar psi and voltage. Other advantages of air compressors is that they allow you to have air locking differentials, and can be paired with an air tank.
An air tank enables quick powerful access to air to seal a tire bead, air cleaning the van, and quiet operation for topping off bicycle tires. It won’t increase time continuously, but if you fill your tank prior to being needed, it will reduce time on the first tire, then the remaining 3 tires will take about the same time as without a tank. Don’t expect to realistically run air tools off one small 12v air compressor like you would with a dedicated garage air compressor which has more than 40 CFM @90 psi and a 5+ gallon tank.
(ARB Tin Air Compressor mounted under hood )
Since the third option with an air compressor is the most common method for inflating tires, here are some tricks to increase speed:
#1 buy a twin air compressor. Keep air filters clean by periodically rinsing the dust off with water and letting it dry.
#2 preferably use some locking air chucks. Make sure your air quick connect for the hose is easily accessible; also make sure you have no leaks with nylon taped fittings and steel braided air hose for reliability.
#3 Install Apex R.I.V. STD valve stem on your rims for larger inlet, faster flow and reduce heat and resistance from compressor.
#4 buy a double or quad hose such as the Morrflate to reduce time connecting hose to shrader valves on each tire.
#5 buy an air tank so that you have already compressed air available which can be filled while driving, prior to being needed at trail exit. It won’t reduce your time for all 4 tires, but depending on the size of your tank, you will get an advantage on the first tire you fill.
#6 simple and free! John at Agile Offroad, who has a lot of experience, told me that opening the hood and leaving engine on reduces time as well. I tried, and the compressor got extra power from alternator and it increased air output!
(ARB quick connect mounted in the grill with steel braided hose)
How to deflate tires quickly?
Here are some tips for deflating tires faster.
#1 fastest way is to replace the valve stem with Apex RPV STD Fast Deflating Valve Stems. The main downside, other than cost, is the installation process.
#2 another option is to buy some automatic tire deflator such as the Coyote air valve deflator. Just like the Apex valve stem, the Coyote deflators will allow you to deflate all four tires at the same time, but the main advantage of those is that they can be adjusted to a pre set pressure so that they will automatically stop deflating once the desired psi is reached.
#3 you can use a simple gauge tire deflator such as the ARB EZ Deflator, but the main dowside to this setup is that you can only deflate one tire at a time.
(Coyote Automatic Deflator Valve Cap)
Owl Vans released in 2022 the Owl Talon wheel which works with double Apex STD valve stems and +30mm offset.
Agile Offroad also released rims in 2023, the HD Overland wheels for Sprinter are flow formed with both Apex STD R.I.V. and RPV valves for quick inflation and deflation. AO wheels are +32mm offset, so you can avoid the spacers if you want with the Agile RIP Kit and there are only 30.5lbs.
If speed isn't your priority, but convenience is, RRE Global and Ti.systems STIS offer a pressure regulator that has hoses that can installed on both sides, it will automatically stop tire inflation once pressure is reached but the cool thing is that it has programmable pre-set tire settings for up to 3 different driving conditions (EX: road, dirt, sand) so you can easily walk away do other things and your tires will be perfectly set for the terrain when you’re ready. Adding a pressure regulator means that you will loose speed of inflation but gain in convenience. You could run one air line separate from the rest of the system directly from compressor for those times when speed is most important.
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As always, if something is missing or you would like to add more information, please comment below to let me know what you are thinking! :)