11.00 air psi, up or down?

[Barrman]

We had the Scout "Report to State" parade in Austin this past weekend. I used the M35A2 to flat tow the M35 Gasser just like I did last year. Last year, the 60 mile drive was super easy. If it wasn't in my mirror, I wouldn't have know the Gasser was back there once I got up to speed. This year was a bit different. Turns were a stressor, staying in my lane of choice wasn't always easy or possible and my max speed was 48 indicated before the Gasser would decide where we went.

Driving in, the road was wet, it was dark and I had to be somewhere at a specific time. There also wasn't much traffic at 0530. So, I used the entire road for turns, let the truck wander where it wanted and basically did what I could to get there without jerking the wheel or doing anything that wasn't smooth.

Driving home, I could see better, the road was dry and full of vehicles. I got aggressive with the steering and made the truck stay in the lane I wanted. I could feel the rear of the Whistler slide or rather bounce when the Gasser wanted to stray. I also kept it around 40-45 indicated at most. Being aggressive seemed to work, but it just didn't feel right in my seat.

I only have about 600-800 M35 flat towing M35 miles. However, I have never had this much of an un easy feeling doing it. Last year, the Whistler had 9.00-20 duals on it. This year it has 11.00-20 XL singles. My first thought was the duals really do make a huge difference. My next thought was that not enough air in the rears. I have them at 60 psi. Then I thought about it some more. (Those of you who drive Dueces know how much quality thinking time these trucks give you) What if the psi was too much? Causing me to bounce and hop along with reacting to every divit and roll in the road?

Gasser tires on the front, 11.00-20 NDTs at 60psi. Same tires and pressure as last year. Same roads too.

We have had so much rain that turning the combo rig around in my place will just make a really big mess, so I un hooked and decided to worry about it next year. What are your thoughts?

Thanks.

One more note. Last year I had the tow bar length set to the 3rd hole. My front tires got crossed up 3 times. I ran in the 7th hole this year and only had them cross up once. (Exact same turn leaving the staging lot both years) Could this 2 feet make the difference in feel because of the extra leverage?

 

[TexAndy]

I was wondering what those tires were.

 

[nk14zp]

I run 50psi in the 1100x20 XL,s on my bobbed deuce.

 

[stumps]

I haven't tried towing with a singled out deuce, but with PU trucks, duals make towing easy, and singles make towing squirrelly. The reason is sidewall flex. When the rear tire's sidewalls flex from side to side, they steer both the trailer, and the towing truck.

I would suspect your tires.

-Chuck

 

[BEASTMASTER]

those tires should be in the 70 to 80 lds range. the suggested pressure should be on the sidewall.

 

[RANDYDIRT]

Are you sure that your towbar angle isn't the culprit? You put bigger tires on the A2 and the towbar angle changed maybe?

 

[BFR]

any weight in the bed of either truck?

 

[gimpyrobb]

Tim, I have found the front tires on the towed truck need to be maxed out on air pressure to keep it tracking well. I also agree with the towing truck needing higher psi inflation, but have not used 1100xls on a truck yet to say for sure.

 

[LanceRobson]

The pressure on the tires is the max pressure allowed for that tire. Almost no application needs the max pressure. The sidewall of the XL is so much stiffer than the 9.00 or 11.00-20 tires that I doubt the lower pressure is the culprit.

Here is a thread with the factory data for the XLs:

http://www.steelsoldiers.com/deuce/40128-correct-11-00r20-xl-tire-pressure.html?highlight=pressure

Sometimes changing the pressure helps, sometimes it won't. Note that both the -10 manual and the towbar TM state in clear language that the towed vehicle must always have an operator to steer. The TM even shows a picture of a towbar rig with the driver in the towed vehicle.

Also, tires with lugs like the Xl's, as opposed to the continuous center rib of the NDTs and NDCCs, don't track well due to the vibration and each lug's attempt to steer the truck as it hits the road. It is pretty common to tear up XLs and similar tires when towing without someone to steer the towed vehicle. The result is galled tires and missing lugs on the outer edge of the tread area. Once those are torn away they'll usually track OK

Lance

 

[Maxgussam]

Did the road's pavement have the "ruts" (usually caused by many thousands of heavy vehicles) in the right lane?
We used to have the wide single tires on some of the converter dollies of our double trailer sets, and the same thing would happen...The tractor and the trailers would stay in the "ruts" created by the millions of dual tires, and the singles would wander back and forth in them.

Just a guess...

 

[motorpoolmedic]

towing

I have tow bar towed hundreds of trucks, thousands of miles safely.
What works best FOR ME is to have the lead vehicle be dueled out in the rear.
This helps overcome MOST swaying isssues.
Having the tires on pavement, I NORMALLY run 90 psi in the dualled 900-20, all the way around. 1100-20 Radial dualled I will run 110 psi. I have pulled jeeps to LWB 5T singled and dualled. Nylon vs radial. High and low psi.
THE main factor in towbar towing is EQUALLIZED TIRE PRESSURE ON THE TOWING AND TOWED VEHICLE! Meaning that the towing (with radial tires ALL be at 110 psi) and if the towed vehicle has single or dualled tires (ALL tires be the same pressure, 70 or 90 or 110 psi)*EQUALIZED*.
Do not run radial AND bias ply tires on the same axle!
Filling the steering gear box with fresh rust free gear lube.
Greasing EVERY zerk on the steering shaft.
Greasing EVERY zerk on the front axle (including the spring perches).
Greasing EVERY zerk in the steering linkage (tie rod ends, ball joints, pitman arm, drag link, EVERYTHING!)
Greasing EVERY zerk on the propeller shafts (unless they are removed).
This helps free up most binding issues. Backing off the brake shoes (to prevent drag: say- on a front steer axle, creating a pull or bind up).
Shorten the tow bar to prevent wander.
Crossed safety chain X to prevent jacknifing in event of tow bar failure.
Lighting to let others know of your intentions WELL IN ADVANCE!
Drive a speed that BOTH vehicles obtain HARMONY. You will be able to tell this speed when EVERYTHING feels right-including your nerves. If something doesn't feel right-STOP/INSPECT/ADJUST. Your life and the lives of the family in the minivan next to you are NOT WORTH THE RISK.
Forget the fact that the recovery is only 30 miles away. It may take 4 hours. TAKE YOUR TIME AND DO IT RIGHT!
Remember to hook up glad hands for brakes (if functional).
CHECK YOUR HUBS AND TIRES FOR HEAT, PINTLE AND TOW BAR/PINS, SAFETY CHAINS, LIGHTING AND LUGNUTS EVERY 50 MILES-RELIGIOUSLY!
A sign on the back with "TOWED VEHICLE" in reflective lettering is a plus.
A pilot car never hurts either.
By the way, if you think that gal in the Cadillac won't pull out in front of you,
SHE WILL! Plan your turns, stops and always stay alert. Pull over and nap if needed.

 

[Keith_J]

Are the singles radial? That would make all the difference, being much less stable in lateral loading. This would reduce the lateral forces which cause the towed wheels to turn. This opposes the caster angle on the towed vehicle which tends to restore the steering angle to zero (straight ahead).

Further compounding the loss of lateral stability is the loss of the duals. Dual wheels are much more resistant to lateral loads.

Finally, bias ply tires have a longer footprint, making them steer much harder.

 

[Barrman]

It was nice to visit with you Andy. Sorry we couldn't talk more. Going out the light and turning onto Riverside has gotten me two years in a row now with the towed front tires turning full lock and not coming back. I think I will go out the back way to Congress next year.

Yes, the singles are radials and the duals last year were bias NDT's.

Yes, the highway had the "10,000 truck have been here" ruts in them.

Since both trucks are now 11.00 tired, the singles actually made the tow bar level instead of pointing down at the front truck.

I thought about sidewall flex and that is why more air first came to mind. However, with both truck being empty and the way the rear of the Whistler was sliding, less air for less bounce and more traction came up too.

I never thought about the wider foot print of the NDT or the off set lugs of the XL's working against each other.

Thanks for all the help gentlemen.

 

[stumps]

It was nice to visit with you Andy. Sorry we couldn't talk more. Going out the light and turning onto Riverside has gotten me two years in a row now with the towed front tires turning full lock and not coming back. I think I will go out the back way to Congress next year.

I have always restrained the steering wheel of the towed vehicle. You really confuse things if you allow it to spin freely. A rope between the brake pedal and the steering wheel has worked nicely for me when towing other vehicles 4 wheel down...

-Chuck

 

[Bob H]

Lot's of good advise above.
My limited experience says your issue was a Deuce with singles pulling one with duals.
You might see an improvement if you were to pull the outside rears on the towed truck.