11 replies to this topic

[buckland]

I have the 2016 Duramax long bed Colorado (mid sized truck) ... I switched tires to 245 75 17 E rated as I go places with a lot of shale stone roads and I at times carry weight. That said...the diesel has a 700 Lbs. over the gas engine up front. While the bed might be empty. What are recommended pressures for the front and rear in typical driving? ....... Then a nice ride with a load? Nothing nuts.... 80 lbs rattles ones teeth.

 

[DesertDave]

I have stock size tires on my truck.  The door label shows the pressures necessary to carry the rated weight.  Any significantly lower load and you might have rough ride and/or center tire wear from over inflation.

 

I did the 'chalk test' on my tires to determine a setting I liked for an empty truck.  Basically run a chalk line horizontally across the tread and do a bit of driving, starting with close to full pressure and no load, and see if the chalk line remains at the inside and outside edges.  Continue the test as you gradually lower tire pressures until you get even wearing away of the chalk line across the tread.  That gets you close to a pressure setting that should carry the weight safely and give you even tire wear.

 

Some tire manufacturers publish tables which show load capacity of a given tire through a range of inflation pressures.  If you have this info, and data from a scale so you know the weight you are carrying, you could do a more scientific method of getting a decent unloaded tire pressure.  This of course would also work with a partial load, or if you have a tire with a far greater load capacity than you are carrying.

 

Just as a reference, since every situation is unique.  My full-load door label said 65 front/75 rear.  Empty I ran it 55 front/42 rear, based on chalk test.  With the FWC on full time, and 1000 lbs of capacity remaining, I just run it 65/75 now.

[Foy]

I don't know the correct answer to this, but I know what has worked for me. I run an 02 F350 SRW with the 7.3 diesel and it supposedly weighs in at 1,200 lbs of engine.

 

OEM tires are 265/75 R16.  The best tires, and the best treadwear life I've enjoyed have been with E-rated Michelins.  I got 51,000 miles out of a set of LTX M/S and just rolled 44,000 miles on the current set of LTX AT-2s, and they'll easily see +50,000 miles. Each set has a max air pressure of 80 psi.  

 

I run them at 80 psi on the highway when loaded and will dial back to "only" 70 psi when lightly laden.For "around town", I'll run them as little as 50 psi.  My understanding is that any tire reaches its maximum weight rating at the stated maximum psi, so my personal "policy" is to run 'em at the max when up and running down the highway.

 

Notably, I do NOT air down below the 70-80 psi when off pavement.  I have run literally thousands of miles on graded gravel county and USFS roads in Montana, Idaho, and Wyoming and have never suffered a cut tire flat (I did pick up a drywall screw once).  I did once air down to around 40 psi, if memory serves, on a long and badly washboarded FS road, but I aired back up as soon as conditions allowed.  My personal experience is having suffered more cut tires when aired down than with them fully inflated (where other trucks in my past were involved with the air-downs).  I think this is the reverse of what most would expect, but it's what happened in my cases.

 

Foy

[JaSAn]

+1 on DesertDave's method.  I use a white grease pen.

 

On thing I would add is to heat up your tires to operating temperature first; cold vs. operating temperatures can vary 5 to 10 lbs.  It takes ~20 miles to heat my tires up in cooler weather.

 

I've gotten 50,000 to 60,000 miles out of the last 3 sets of tires using this method (depends on tread: highway tires last longer than A/T tires).

 

jim

[smlobx]

I thought the OP was talking about full size trucks! j/k..

I'm in the same camp as Foy with my Diesel F-350 SRW. My door card says 65/75 f/r and when loaded that is what I run with. When empty I will drop the back to 70 psi. Keep in mind that my truck empty weighs almost 8000#'s.

Having said that the only time I seriously drop my pressures is when I drive on the beaches of the Outer Banks in NC. For those who don't know this is some of the softest sand known to man and many a vehicle gets stuck there. In fact in order to get a permit to drive there you need to carry a shovel, tow strap etc. when I run the beaches I will air down to 35/30 and if I start getting stuck I will immediately stop and drop it another 5 psi. In over 25 years of driving these beaches I have only gotten stuck once. I have yet to drive there with my Hallmark on as I have a place to stay there... Surprisingly the best type of tire to run there is one with the least amount of tread on it which will allow the tires to float over the sand as opposed to digging in.

If you want to see some videos on how not to drive in soft sand you can google Oregon Inlet Idiots like this one...
https://m.youtube.co...h?v=Ol8YuZcvoAs

Edited by smlobx, 14 July 2016 - 09:40 PM.

[Foy]

Well, yes, the more correct statement is the only place I air down when off roading is on the NC beaches, where it's a must.  I used to take my Isuzu Trooper down to 13-15 psi, the pressure at which popping a bead is a real possibility if you're not very careful about tight turns, etc.

 

Good video!  It shows, for better or worse, the realities of there being a relative handful of miles of beach driving along the entire East Coast and the proliferation of people wanting to run the beach.  I wonder if that video was shot at the old #4 ramp at Oregon Inlet or up at Carova?  I stopped going to Carova because of crowds like that, and if that's Oregon Inlet #4, looks like I need to cross that off of my list, too.

 

Foy

[2tallDA]

Front axle 4400#,rear 4000# with camper.

I run 60 psi all the way around with 285-75-17 Toyo AT's. They wear evenly with stock 8" rims.

Unladen I run 50 front and 40 rear.

[Bigfoot]

What do you guys do with the TPMS when you air down? Just let it give annoying warnings?

 

And what do you use for airing up? Truck tires hold a lot of air and portable air compressors take forever. 

[smlobx]

Foy- this was just sent to me by a frien who lives in Buxton...
The Point (perhaps the best place to surf fish on the east coast) was opened up to vehicle traffic two days ago after the bird nesting season and this happened....

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[PaulT]

Well, yes, the more correct statement is the only place I air down when off roading is on the NC beaches, where it's a must.  I used to take my Isuzu Trooper down to 13-15 psi, the pressure at which popping a bead is a real possibility if you're not very careful about tight turns, etc.
--snip--
I stopped going to Carova because of crowds like that, and if that's Oregon Inlet #4, looks like I need to cross that off of my list, too.
Foy

I had many wonderful times driving the Outer Banks for surf fishing in the late 60's and early 70's & remember learning the hard way about airing down to 12-15psi to avoid getting stuck in my Wagoneer. Had only a bicycle hand pump to air back up. Youth certainly was an advantage.

As I recall, it was about 17 miles across the sand up to Corolla. At that time, only a one room PO and the hunt club with that magnificient green roof and the arched foot bridge were there. Using Google Earth to take a look at the area a few years ago really made me wish we had been successful in adding the area to the National Seashore. Took a lot of photos on the ground and from the air that went into a presentation & booklet showing landscape & wildlife for Udall & others. Wonder if the effort just encouraged its development as a vacation spot for the DC elites. (Sigh)
Paul