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ReTire
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Posts: 129
Registered: 9-16-2018
Location: PNW
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Thanks guys. Gonna have to do the chalk test. Never heard of it before. I knew Les Schwab was over inflating my tires!
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David K
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Quote: Originally posted by ReTire  | | Thanks guys. Gonna have to do the chalk test. Never heard of it before. I knew Les Schwab was over inflating my tires! |
From 2012:
https://www.tacomaworld.com/threads/chalk-test-dynapro-atm-a...
I began running them at 37 psi (they are rated at 44 max), and after the chalk test I dropped to 35 psi, but dropped one more psi so 34 is the sweet
spot. The chalk is the kind they sell for kids to mark up sidewalks... graffiti training!
The stock BFGs were rated for 36 max (I think) and Toyota recommended 29 front and 32 rear. The Hankook DynaPros are a far better tire than the BFG
Rugged Trail TAs and rated for more weight, etc.
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Timinator
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If you have one of those IR thermometers that shoot a beam, or one for steaks and such with a small sharp point, you can use that too. That's what we
do for figuring PSI for racecare tires. After driving at freeway speeds for a several miles, just stop and shoot the left, middle, and right side of
the tires. Hot center is over inflated, hot sides is under inflated. Pretty quick and easy.
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4x4abc
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| Quote: Originally posted by Timinator | If you have one of those IR thermometers that shoot a beam, or one for steaks and such with a small sharp point, you can use that too. That's what we
do for figuring PSI for racecare tires. After driving at freeway speeds for a several miles, just stop and shoot the left, middle, and right side of
the tires. Hot center is over inflated, hot sides is under inflated. Pretty quick and easy.
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works very well
chalk line is much faster
for the German accuracy freaks among you - I would combine the 2 methods
start with setting psi according to chalk line
then fine tune with a freeway run and the infrared temp meter
Harald Pietschmann
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bajatrailrider
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I'm using d rated 33s. Dirt all off road 16psi. Road street 26 psi. Hope this helps
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4x4abc
Ultra Nomad
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Now - how fast can you go with deflated tires?
You just played around at Davids Shell Beach with 10 psi in your tires
then you run out of beer and need to drive to San Felipe
not on the beach like in the old days, but on pavement
20 miles
do you have to pump your tires back to 30, or can you just go get beer on 10 psi for 40 miles roundtrip?
soft tires flex a lot
the faster you go the more ften your tire flexes per minute
that creates heat - heat will destroy your tires
I had the same problem for years after finishing trips on the Rubicon Trail
another 40 miles of pavement needed to be covered to get back home
an average of 40 mph with brief peaks of 60 mph worked just fine
for the last 30 years
to make sure your tire is not getting too hot use the back of your hand (the back of your hands s more temp sensitive than your fingertips) and test
the sidewalls
so, you don't have to always re-inflate your tires when hitting pavement
especially important for people without a compressor or a broken compressor (they tend to do that)
you can drive to the next gas station even if it is 100 miles away
just keep your speed down
Harald Pietschmann
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mtgoat666
Select Nomad
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Isla San Martin
Woke!
“...ask not what your country can do for you – ask what you can do for your country.” “My fellow citizens of the world: ask not what America
will do for you, but what together we can do for the freedom of man.”
Prefered gender pronoun: the royal we
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vespaio
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Harald,
Regarding tire pressure in an off-road trailer. I've heard both options:
1. Air down. This seems to me to be counter productive since airing down will increase the footprint, increasing the traction, making the towing
vehicle work harder.
2. Don't air down. This would seem to decrease the trailer's traction, making it easier to tow.
Both options were told to me by the same person over a period of months. Obviously one is less correct than the other.
Your opinion?
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Maderita
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"Traction" is not the issue. That is for the drive axles on your tow vehicle.
You want "flotation" in the soft stuff (sand, silt, mud). Air down your trailer tires. That increases the tire footprint, helping it float, with less
resistance for the tow vehicle.
Towing a trailer through sand without airing down is like dragging an anchor behind you.
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Maderita
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Additional benefits of airing down tires off road:
The tires will absorb some of the shock from ruts and bumps, making less strain on the trailer components and contents. Lower air pressure makes it
less likely to get punctures/blowouts due to sharp rocks. However, airing down too much may expose the sidewalls to punctures/damage.
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vespaio
Junior Nomad
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It all makes sense, so airing down it will be. Since the trailer will have street tires, sidewall damage is always a possibility.
Thanks.
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AKgringo
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It all depends on the load! When I pull my off road trailer behind my Kia Sportage, I run the same wheels and tires on the car and trailer
(225/75/15).
Since both the car and camping stuff is a light load, I run 24 psi in the Kia, and 10 psi in the trailer to get the same foot print. That is on
pavement, offroad I drop the Kia psi as needed, but don't mess with the trailer anymore.
An almost flat tire is easier to pull through sand than a fully inflated one that will be pushing a sand berm ahead of it, so that you are always
trying to climb out of a hole!
For what it is worth, I have hauled a 300 gallon water tank in that trailer, and only had to go up to 15 psi to carry that load (2400 lbs)!
I followed over 500 miles of the Baja 1000 course with that set up, and 10 psi keeps the trailer from flying around so much on all the whoops, topes
and vados!
If you are not living on the edge, you are taking up too much space!
"Could do better if he tried!" Report card comments from most of my grade school teachers. Sadly, still true!
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4x4abc
Ultra Nomad
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Location: La Paz, BCS
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| Quote: Originally posted by vespaio | Harald,
Regarding tire pressure in an off-road trailer. I've heard both options:
1. Air down. This seems to me to be counter productive since airing down will increase the footprint, increasing the traction, making the towing
vehicle work harder.
2. Don't air down. This would seem to decrease the trailer's traction, making it easier to tow.
Both options were told to me by the same person over a period of months. Obviously one is less correct than the other.
Your opinion? |
when it comes to tire pressure, there are a lot of opinions
here is the knowledge:
on anything soft you must increase the footprint of the animal
Camels have very big feet for that reason
humans learned to use snow shoes and ski
if you don't
you will sink in
that makes moving forward harder or impossible
the softest sand I know of in Baja is at the north end of San Francisquito.
a few years back a good friend of mine needed to bring a trailer to San Francisquito
he aired down after he got stuck
he remained stuck because he did not air down the trailer tires
remember: Camel ?
he was moving just fine once all tires had appropriate footprint for the condition
traction is not involved - more footprint reduces resistance
as you can see looking at the tire prints in front of Karl's rig, the rest of the group only left shallow imprints and moved easily over the soft
sand.
Karl's tires, however, are sunken in very deep (about 20psi) and he can't proceed
and the off-road anchor (trailer) did not help either
Harald Pietschmann
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vespaio
Junior Nomad
Posts: 41
Registered: 11-6-2019
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As they say, "a picture is worth a thousand words." I'm convinced.
Thanks, Ray
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4x4abc
Ultra Nomad
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Here is another one for sand: Drive as straight as possible!
Even with deflated tires.
Driving straight makes the rear tires follow in the same already compacted sand channel the front tires have created.
With the right (low) tire pressure you are just cruising along.
But by initiating a turn, the rear tires leave that front tire channel and each of them will now create their own rear tire channel and thus will have
to doze a small berm of sand in front of them.
That increases the resistance by 100%.
Increasing the chance to get stuck.
The tighter the turn the higher the resistance.
Of course you can't avoid turn forever - but be gentle
Harald Pietschmann
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John Harper
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I drove close to 300 miles of dirt FS roads in Wyoming last summer with tires at 20 psi cold (24 psi hot). Lots of small sharp rocks in many areas.
Did not have one flat tire the entire trip, but did repair 3 other's flat tires, none of whom was driving on deflated tires. Normal highway inflation
for me is 34 psi cold.
Good enough proof to me that deflation helps prevent flats.
John
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David K
Honored Nomad
Posts: 64490
Registered: 8-30-2002
Location: San Diego County
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Mood: Have Baja Fever
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Deep sand
Before and after deflation of tires in 4WD (34 psi to 15 psi):
Human foot prints go deeper into sand than the truck with deflated tires:
Tires are Hankook Dynapro ATM 265/75-16 (44 psi max)
As noted above, deflating of graded dirt roads will improve the ride and reduce flats... I had for years refused to air down except for sand and would
get many flats from sharp rocks (I like to drive fast)! Going from 34 psi down to 20 psi has almost eliminated flats for me. Going slower helps too...
It also assists in traction when climbing tough, steep grades.
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4x4abc
Ultra Nomad
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the air in your tires is the most underrated tool for safe, trouble free off road travel
but you can not mount it on your roof rack to show off
Harald Pietschmann
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gnukid
Ultra Nomad
Posts: 4410
Registered: 7-2-2006
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| Quote: Originally posted by 4x4abc | Here is another one for sand: Drive as straight as possible!
Even with deflated tires.
Driving straight makes the rear tires follow in the same already compacted sand channel the front tires have created.
With the right (low) tire pressure you are just cruising along.
But by initiating a turn, the rear tires leave that front tire channel and each of them will now create their own rear tire channel and thus will have
to doze a small berm of sand in front of them.
That increases the resistance by 100%.
Increasing the chance to get stuck.
The tighter the turn the higher the resistance.
Of course you can't avoid turn forever - but be gentle
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This is one of the best tips, drive straight don't turn in the sand, and when you do turn plan where you going to turn to ensure it isn't deep sand.
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defrag4
Senior Nomad
Posts: 536
Registered: 2-5-2011
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| Quote: Originally posted by 4x4abc | the air in your tires is the most underrated tool for safe, trouble free off road travel
but you can not mount it on your roof rack to show off |
im going to have to come up with some aftermarket "overlanding" air that u can mount on ur rack after u take it out of your tires
will sell like hotcakes
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