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Date:         Sun, 10 Aug 2008 02:30:39 -0700
Reply-To:     Randal Jett <randal_jett@YAHOO.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Randal Jett <randal_jett@YAHOO.COM>
Subject:      Re: Trailer loading and tire pressure testing
Content-Type: text/plain; charset=iso-8859-1

I can't believe I just messed that up.  Apologies.  The 90/10 rule is for passenger to DRIVER distribution, no the other way around.  Sorry about the confusion.  The weight off-set needs to be for the initial wave, therefore is 90 on the PASSENGER side and keeps the rig pulling straight through the turbulent periods of passing wind currents. The idea of having someone ride in the back was suggested to monitor the wheel bounce.  If anyone is planning to do this, I strongly suggest that they concentrate themselves on to the passenger side IF big trucks passing are expected.  Avoid the tendency toward the seemingly obvious loading of the trailer down the middle as this WILL concentrate the post-pass turblence and risks of excessive wiggle in the tail of the trailer unit. Randal ----- Original Message ---- From: Randal Jett <randal_jett@YAHOO.COM> To: vanagon@GERRY.VANAGON.COM Sent: Sunday, August 10, 2008 3:53:21 AM Subject: Re: Trailer loading and tire pressure testing My understanding is the possibility exists to counter-act the cross-wind coefficient of the eighteen wheelers that is so hard on little trailers.  My rig is small unlike yours, but this information will still apply.  The big trucks when they pass create a 'wake' like I want when I paddle hard in my canoe on a windy year.  This is the part that can be upsetting to the van/trailer combo.  By packing the trailer with an uneven driver's side to passenger side load, undesireable van/trailer oscillation 'wake' effect is negated thereby avoiding the dangerous swerve, swoop, and squat post the big truck pass.  In my family, we practice trailer loading at 90% weight distribution on the driver's side of the axle.  This is where most of the work keeping straight is done and has proven to be what my ancestors needed to keep going on the highway, when big trucks pass.  I come from a trucking family.  The tricks to trailering with ease were learned the hard way, but I'll skip those details.  The 90/10 split, what this has done for us is resist the push of the initial truck wave and that keeps the trailer in a straight line in spite of the high cross-wind throughout the initial stage of the truck push pass.  One might think this would tow uneven, and on little tires or with improper tounge length, there could be an argument, but on tires 13" and larger, this is nothing less than a trailering law for truckers and vans alike.  Bearing in mind well over 300,000 miles of trailer packing and towing in the '80's alone in my family, we learned together how to pack to resist the wind.  Your tire size is sufficient to benefit from what I am saying now. Not that it's powerfully important, but there are some arithmetic errors in the calculations below.  I'm not going to bother with correcting them.  I will ask for a re-weigh on the bathroom scale under both sides of the axle (one at a time) and take a picture of the digital readouot.  10% on the passenger side-wheel of the axle is plenty.  Trust me on this -- you can skip the test drive as it has already been proven to be true.  Texas Trailering 101 course completed in 1987 with nothing but successful hauls since that time. Watch it with the tongue weight.  I lost a trailer once due to a tongue failure at interstate speed!  Snaped right off clean.  Luckily, yet not surprisingly, nobody was hurt.  That trailer was hooked to our family bus, a Trailways Silver Eagle pulling a Well-Cargo dual-axle trailer with a side door.  That was one big and heavy trailer!  Anyway, a guy signaled us to pull over, and said, "uh...were you'all pulling a trailer?"  Puzzlement all around, "we don't have a trailer?"  Long story short, it broke just forward of the ball, snapping the safety chains, and careened for quite a distance on it's own down the pavement of I-70 in rural INdiane, is evil to think of what could've happened if it didn't find it's own way into the median, still traveling at speed.  Remember, it was a dual axle trailer well-balanced front to back so it rolled pretty level, a long, long way.  Here is where the 90/10 split had an unexpected pay-off.  Mostly all by myself, I  found several deep gouges in the payvement, across the standard lane, then a couple streaks on the passing lane, and off it went into the median!  The proper weight (ninety percent) over the driver's side axle had helped to keep that trailer out of trouble, causing it to self-guide into the safety of the flat grass in-between east bound and west bound.  Like it had a mind of it's own!  You might think it just came to an easy rest.  Nothin' doin!  It bounced a couple of times, diggin g big holes in the ground from the tongue, then a huge hole where the tongue stopped the trailer's forward progress, flipped forward into the air in what must've been a huge arc, levered on the tongue, expelled contents through the front of it (where there was no door), and sailed through the air 40 feet up-side-down before landing on top of most of the trailer contents.  What a mess!  Mud, rain, at night, hours of waiting for a rental van pick-up never mind the remote possibility for a clean-up and moving service.  Cold.  The Yamaha CP-88 electric-acoustic concert baby-grand piano survived in it's anvil cases but it did need a tune before the next gig.  That was years ago but seems like only yesterday we installed a bigger ball hitch throat, bigger safety chain, and rebuilt the trailer. So, go with the 90/10.  It works. Randal former roadie ----- Original Message ---- From: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM> To: vanagon@GERRY.VANAGON.COM Sent: Saturday, August 9, 2008 10:23:44 PM Subject: Re: Trailer loading and tire pressure testing hi mike. I never go as low as 15 or 20 psi unless it's for going on sand or something. I also liked that guy's rule of thumb that if the pressure goes up more than 10 % after a run, and that would have to mean getting the tire warmed up on a warm day .....if it does that it was underinflated in the first place. Never heard that one before........but I like the concept, and it makes sense. LOL ! . ..thanks for the humor on the 'resemble that remark' - make me laugh- thanks ! I needed that. scott fwiw..... for years old american cars would specify tire pressure like 22 psi.........or in the 20's for sure ......for a smooth ride I suppose. Back in the 50's and 60s .........and even then that was unrealistic. ----- Original Message ----- From: "Mike Elliott" <camping.elliott@gmail.com> To: "Scott Daniel - Turbovans" <scottdaniel@turbovans.com> Cc: <vanagon@GERRY.VANAGON.COM> Sent: Saturday, August 09, 2008 1:55 PM Subject: Re: Trailer loading and tire pressure testing > Hi Scott, > > Hmmm. The chart at http://tinyurl.com/6lg2oy says that 15 psi correct for > 670 lbs per tire. I'm way under that, even. The tires are rated to 1360 > lbs at 50 psi. > > Maybe you're right -- I should ignore the chart and just put 25 psi into > the tires. > > You wrote, "I think you're 'trying to hard' or being obsessive." > > I resemble that remark! > > -- > Mike "Rocket J Squirrel" Elliott > > > > > On 8/9/2008 1:43 PM Scott Daniel - Turbovans wrote: > >> i think you said the max inflation pressure listed on the side of the >> tires was 35 psi ? >> >> anything like 15 or 20 psi sounds way way too low for a 13 inch tire to >> me. >> I'd do 25 psi cold, and not worry about it. >> >> I heard another 'trucker's rule' about hot tire pressures. >> 'never let air out of a hot tire' .............the idea being, I believe >> , is that  you don't now how low it will be once it's well coooled off. >> So I just set them at something reasonable cold, >> and drive. >> If things are harsh or bouncy, then I let some out, 3 psi at a time say. >> works for me ! >> I've towed trailers and vans and cars just countless times, for decades. >> I think you're 'trying to hard' or being obsessive. >> I suggest put 24 psi in them cold.......nice even # that.........and head >> on out. >> Super that you did a test drive ! >> I always carry a spare tire for trailers or anything towed too. >> scott >> >> >> ----- Original Message ----- >> From: "Mike Elliott" <camping.elliott@GMAIL.COM> >> To: <vanagon@GERRY.VANAGON.COM> >> Sent: Friday, August 08, 2008 12:35 PM >> Subject: Trailer loading and tire pressure testing >> >> >>> Hi all, >>> >>> I don't to join the legion of unskilled trailer haulers who find >>> themselves in a terrible jam because they were dozing in Trailering 101. >>> >>> So if anyone wants to check my work to see if I overlooked something, >>> that >>> would be helpful. >>> >>> TRAILER: 270 lbs. (Small fiberglass-bodied single axle utility trailer. >>> Empty weight: 270 lbs. This was derived from weight on tongue = 30 lbs, >>> weight on one tire 120 lbs. It's safe to say that the other tire had as >>> much weight on it.) >>> >>> PAYLOAD: 218 lbs. >>> >>> TOTAL COMBINED WEIGHT: 488 lbs. >>> >>> The rule of thumb seems to be to have 10% to 15% of the gross weight on >>> the tongue, so I balanced the load to get 55 lbs on the tongue. >>> >>> TIRE PRESSURE >>> >>> Too much pressure = bouncy ride, too little = hot sidewalls and possible >>> kablooey. Each tire is carrying (488 - 55)/2 = 240 lbs. These tires are >>> ST175/80R13, and according to the load inflation chart at >>> http://tinyurl.com/6lg2oy 15 psi is more than enough. Refer to the chart >>> if you don't believe me -- these are beefy tires for such a little >>> trailer. Heck, 15 psi is good up to 670 lbs per tire. >>> >>> So I aired each tire to 15 psi and took the loaded trailer for a 7 mile >>> ride, half of it on the freeway. At the end of the ride, the sidewalls >>> of >>> the van's tires (aired to spec) had risen to 97F (ambient here is around >>> 76F), and the sidewalls of the trailer tires read about 90F. This >>> suggests >>> that the tires are not underinflated, which is in agreement with the >>> load >>> inflation chart. >>> >>> However, the pressure in each tire had risen to 20 psi, a 33% increase. >>> >>> A list member had p-mailed me a couple days ago about a tire pressure >>> rule >>> of thumb: if the pressure goes up more than 10% after a fast 5-mile >>> drive, >>> the pressure is too low. >>> >>> So...according to the rule of thumb, the tires are underinflated. >>> According to the chart, they are nowhere near being underinflated. >>> According to the comparison to the sidewall temps of the van's tires, >>> they >>> are not underinflated. Anyone want to comment on that? >>> >>> Oh -- by the way, the trailer towed like a dream. No side to side >>> oscillations which indicate that there is too much weight to the rear, >>> and >>> no excessive bouncing. It followed along like a little sweetheart. >>> >>> -- >>> Mike "Rocket J Squirrel" Elliott >>> 71 Type 2: the Wonderbus >>> 84 Westfalia: Mellow Yellow ("The Electrical Banana") >>> 74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano >>> KG6RCR >>


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