Tire pressure for trailer tires

[jadatis]

If you use the chalk test, dont go on until sides wear off more then middle of treath, then you probably are to low at the lowest pressure the chalk wears off evenly , so to much heatproduction, wich cources damage to tire. Begin high and go lower in steps until chalk wears off equally , then stop.
This gives you the reserves it needs.
A radial tire stays with its widht of treath on the ground in a large range of deflection, so pressure for a load.
But the heatproduction ( where the tire-and car-makers all do it for ) is a smaller range.
Heatproduction is a product of number of cycles a second X heatproduction a cycle( courced by the deflection and flexing back of every segment of the tire about 10 times a second at speed of about 80km/50m/h). Lower speed > lesser cycles a second> more deflection allowed> lower pressure allowed for the same weight on tire. I think that for in Sand/Mudd the tire has a larger ( not flat) contactpach to the ground so can bare more weight at the same deflection so same pressure for weight, wich explaines the 50% pressure needed then for same speed on road.

 

[wagex]

lower tire pressure offroad helps roll over obstacles easier and its alot easier on the trailers suspension and the contents of the trailer.

as for tire pressure with these little trailers its hard to say for sure, i run 265/75r16 if my trailer is empty i have to air down to like 10psi for the highway or it bounces down the highway like a basketball. when its loaded down completely (about 1200lbs) i run 25-33 psi still playing with that.

 

[sunnybean]

M416 with lid, rtt, and gear runs best down the road right at 20psi. Any higher and it bounces too much.

 

[teotwaki]

I am a regular guy, not an engineer. Someone here posted about traction. What does traction have to do with anything when off road on a vehicle that is not self propelled? I would think that a skinnier pizza cutter tire would do better off road on a trailer than a wide tire.

----snip----

I used to run tires with more of a street tread on my trailer as I was only considering the minimizing of on-highway rolling resistance. After running the trailer for almost 7 years I can say that traction is a factor and I did have situations with sideways slippage on those original tires.

This set of shots is from an area in Moab near the White Rim Trail after the snow melted

The street tread tires became big slick donuts with no real traction and I saw the trailer slipping left and right behind me on the muddy trail as I went uphill and around corners.

Now I run Duratrac tires on the trailer and have not seen the tires become coated in mud that could not be flung off with modest speed. I have found that having a good self-cleaning tread is as important on the trailer as it is on the truck. Having the same tires as the tow vehicle also gives you more spares for the tow vehicle in an emergency.

I cannot say with certainty the weight of my trailer when loaded but it is heavy. I do have both springs and shocks in the suspension but even then on highway I run 32 psi and off-road I will drop it to 25 psi so the tires will more easily conform to rough trails and present less resistance for the tow vehicle to overcome.

http://suntothenorth.blogspot.com/2014/02/my-expedition-vehicle-trailer.html

 

[captwoody]

After cutting across Anza Borrego Badlands(crossover trail) yesterday and picking challenging lines I learned a few things at trailer expense. (1.)You cant do deep dips straight on if deeper than 3 feet or you taco trailer and drag it on rear trailing edge.(2.) just because jeep will keep pulling it don't keep doing that or your tongue will get bent upward.(3.) My welds and bolts are more than strong enough. (4.)Bypasses are your friend when towing trailer. So now just need to repair frame (lightweight harbor freight c channel collapsed from tongue being gusseted compressing 1/2" angling tongue upward) I intentionally was pushing trailer to see what weaknesses I could find. Larger tires will minimize rear of trailer dragging and Low tire pressure is my friend. If you want to do Rubicon style trails full length heavy tongue is needed or front channel will dent from pressure. Tentrack, RTT,Aluminum side covers, and trailer contents all did great. Averaged 14.6 mpg on 220 mile trip with 30 miles being 4x4 trails. This is same mileage I got doing same loop without trailer but this time I used my rear locker in 2x except when I needed traction on ascents, descents. Trailer tracks like a dream and runs very smooth with 20lb air pressure on highway and bearings or tires did not get warm at all

 

[teotwaki]

------snip------------ (1.)You cant do deep dips straight on if deeper than 3 feet or you taco trailer and drag it on rear trailing edge.---snip-----

This is where a trailer design should consider reasonable approach and departure angles which include the means by which the trailer is attached to the tow vehicle's receiver.

Some examples from some Expo trip reports

 

[captwoody]

The bypasses looked like those I made the mistake of crossing ditches over 6 ft deep with 45 degree approach departure angles in the badlands on the crossover trail. I forgot to take in consideration the taco effect. I had taken trailer from Canebrake on S-2 up Canyon sin Nombre down Diablo drop off out fish creek to the 78 and it did fine just some binding with a 2" ball. Pure inexperience and operator error when I crossed yesterday. Had that lets see how much this can do attitude, OOPS MY BAD. Well lesson learned will repair and move on.I was planning on adding stronger cross members when I add axle/spring retro fit anyway. And tongue is more than strong enough. So I have the off road tires coming and will not do mud until change and your photos make it clear on what is reasonable and will make attempts accordingly. should have listened to little voice (TAKE THE BYPASS)

 

[captwoody]

Repairs made good to go ,now work on picking better lines. Once axle gets here for swap will finish welding up once install passes test drive

 

[Mr.Incredible]

I just had my trailer weighed at a heavy duty tire shop that services a lot of RV's, Semi Trailers, etc. When they saw my trailer weight which is 1440 lbs. dry, he told me to run the tires at 10-15 psi. I told him I had them at 20 currently and he said, "I wouldn't run any more than that". I'm running 35x12.50r17 on my Jeep and trailer. Just food for thought for everyone who is running high psi in their trailer tires.

 

[old_CWO]

Some tire manufacturers will publish load inflation tables to help zero in on PSI per LB: