85 replies to this topic

[craig333]

8k rig. I run 80psi on the street. 40 offroad but rarely. Probably should air down more often but I'm lazy. 

[Lighthawk]

Depends upon your situation.  I typically will got 35F/45R when driving DV washboard or similar while driving a 06 Tundra/Hawk.

We've driven that combo on many a dirt road and even done the last 20 miles home running those psi.  Normal highway is 45/55.

On the extreme side, while buried in deep mud, I've dropped to 18 PSI when maximum short term traction was required.

[Advmoto18]

Depends on terrain.

 

Outer Banks National Seashore (everything from deep sand to hard pack) I've gone as low as 28psi in the rear, 30psi up front on my LRE Toyo ATII 295-16s on my F250.

 

Normal tarmac psi is 65 and up to 75 if pulling the boat with camper in the bed.  80 psi is max;  embossed on sidewall.

 

The important thing to remember...

You must air up before driving normal highway (tarmac) speeds after airing down.  PSI represents a given volume of air in the tire carcass.  Not enough air and the tire will very quickly over-heat resulting in excessive wear and possibly failure at highway speeds.

 

I use this little pump to air up.

Edited by Advmoto18, 14 November 2015 - 12:21 PM.

[buckland]

That pump looks great. I use a Slime compressor and it works but... that one is so packable. I also ride motorcycles and that would be a great small addition to the pack. Thanks for the steer. BTW the Cape Cod National Seashore has very strict guidelines for tire pressure. I will paste below. (Pop-up camper aren't allowed to camp on beach as the camper needs to have a permanent grey and black water tank equal to the fresh water tank size. )

Tire Pressure:

You are required to decrease tire pressure before entering the beach ORV. Tire pressure is critical for successful oversand driving. 11 p.s.i. is recommended. Friction may cause pressure to increase while you drive making it necessary to stop and reduce pressure again. Your beginning tire pressure should not exceed 15 p.s.i. An air compressor for inflating tires is located in the parking area between the north and south access areas at Race Point. 

[JHanson]

An 8,000-pound rig will need higher pressure than a 6,000-pound rig, whether on the street or in soft sand. Chalking your tires is still the best way to determine correct street pressures in my opinion. Our 6,000-pound Tacoma/FWC likes 45 psi in front and 50 in the rear on the street; in soft sand I would not hesitate to go as low as one bar (14.7 psi). For most of our off-pavement driving, 25-30 psi all around works well.

 

It's really critical to have a good compressor, as well as an easy way to air down tires. If the process is a 30-minute epic you're a lot more likely to skip it. Proper airing down is good for everything—your comfort, the vehicle's well being, and the trail's as well.

[Wandering Sagebrush]

I just bought a Viair 400 P from Amazon. It will handle larger tires, goes to 150 PSI, and has good reviews. It replaces our Slime that works ok, but takes a long time to bring the big tires up to pressure.

http://www.amazon.co...r/dp/B000X9AXR8

http://www.fourwheel...ir-compressors/

[ntsqd]

I've found that the off-pavement ride is considerably better at 40 psi vs. 50 psi. I've yet to go below 40 as it does what I need it to do and I don't feel like pushing that boundary.

 

 

This thread is meaningless without any rig/weight specs.

 

OK, Our truck prior to the camper and the 315/70R17's scaled at 6470 lbs. ('96 CTD ClubCab long bed) w/ unknwn weight 6.5' Phoenix pop-top. Never felt the need nor seen any evidence that 50 psi was too low for the pavement. Any more pressure than that and the outer edges of the tread start to pull up and I don't see even wear across the whole tread-face. That and more the 50 results in the pavement ride circling the drain....

 

My '84 Xcab Toyota with a shell, unknwn weight, 33-10.50 A/T's normal pavement @ 30 psi. Even 32 psi again pulls the outer edges of the tread up. Off pavement, if I air down at all, is 20 psi. Never felt the need to go lower and IH8MUD!

[craig333]

Jonathan has a good point. I do have a compressor but it is a 30 minute ordeal to air back up. Thats a large reason I've been looking at CO2 rigs.

 

Its a bit easier on Jeep runs. Everyone stops and airs down and everyone stops and airs back up. Solo I can easily convince myself its not really necessary. 

 

Weight is crucial. On my Jeep I'll normally air down to 12 psi, 8 if its hard core rock crawling. I've even gone as low as 2psi for snow but you can almost expect to lose a bead there. 

 

I've probably told the story where I was towing my Jeep on a muddy (raining hard) road when I lost traction. No way to disconnect the Jeep with tension on the tow bar. It wasn't fun airing down in the rain but once I did I just drove on out. 

 

I'm not sure just how low I could go on the truck. Maybe I'll go do a test in the driveway. 

[Advmoto18]

I simply accept the fact it is going to take ~ 40 minutes to air up my 295/70-16s to 65 psi.  The Best Rest pump is rated to 100 psi and was carried by many Marines in their Humvees in A*stan.   No doubt there are better air up compressors for truck tires since this is primarily a motorcycle tire pump or for use to top off vehicle tires more than air up.

 

Here is a somewhat dated chart for various compressors and air up times from 10 to 35 psi.

 

 

Jonathan, are you using the pump plumbed to your air locker for air up?

Edited by Advmoto18, 14 November 2015 - 07:10 PM.

[Wallowa]

Solid discussion and valuable..Lighthawk your numbers make sense and are the closest to what I will have once we get the Hawk.

 

An aside:  I carry and use the CyclePump mentioned above for my '07 BMW GSA which I only ride off road...I maintain high pressures off road to lessen punctures and to protect rims 37f/42r with a total load of about 250 lbs of rider and gear...my thought about the Cycle Pump is that it is a great little pump but the volume of air, not pressure, would require long run times for my Toyo AT II..265/75 x16 tires and this would generate a lot of heat...which the pump would handle in the short term...but heat is not the friend of a compressor.

 

Will probably pop for a larger volume compressor...plug kit and compressor is basic get-home gear.

 

Oh yes, C02s?   That would take a 5 gallon bucket of cylinders to even start to inflate a truck tire...

 

Since my tires are only 6ply and "C"s...no lectures please...I will keep them pumped up unless absolutely necessary to crawl out of sand, mud or snow.

 

Again thanks to all for your input...good stuff.

 

Phil

Edited by Wallowa, 14 November 2015 - 10:40 PM.