Re: [VAL] Back to steel tire stems and the why's and what-for

[Gerald <geraldj@xxxxxxxxxxx>]

> The LT decimates "Light Truck" tires doesn't it?  I've seen lots of utility 
> trailers using car and truck used tires before.  Would I run light truck 
> tires on my Airstream?  No, I would not.
> 
LT tires were the tires of choice in the 60s. Special Trailer tires were
not made. LT being the choice as made for load hauling, generally with
more plies than soft riding car tires. A tire's load rating depends on
the cross section area and the air pressure. The maximum pressure
depends on the ply rating.

> You do say your tires have an "8-ply rating" but that does not mean there 
> are 8 plies but you knew that.  I suspect that the 8-ply rating is saying 
> that the tire sidewalls are pretty firm but that's about it.
> 
Used to be tires made with cotton or nylon fabric had the ply count. No
rating. Going to stronger fabric like polyester which has about twice
the strength of cotton or nylon allow tires to be thinner but at least
as strong, hence the ply rating label.

> Because you choose to use LT tires and the 45 psi works for you does not 
> mean it's the correct thing to do though.  LT is for Light Trucks, that is 
> what they were designed for.  I suspect that your trailer could put those LT 
> tires through some tests they would not experience if they were on a truck 
> instead of a trailer but I'm not a tire engineer either.
Turning square corners with a tandem axle trailer does tend to rip the
tires off the rims sideways. Not a problem with the single axle trailer.
I don't think side thrust of a trailer otherwise is different than on a
tow vehicle that stands tall.

> 
> Running LT tires in the first place at 45 psi does not mean you are immune 
> to rapid heat build-up should the sidewall begin to flex due to low air 
> pressure.  This could happen and you'd never know it unless a slightly 
> smoking tire that was nearly flat was pointed out to you or you heard the 
> loud explosion when the pressure built up enough to wipe out the tire and 
> lots of sheet metal.

Tires heat from flexing and internal friction. Bias ply tires heat more
because the plies rub against each other as the tires flex. Radial tires
heat the least because the lay of the fabric prevents that rubbing. The
fabric in radial tires only bends so it heats a lot less. My first set
of radials heated more from sun than from flexing which is to say they
didn't heat much.
> 
> Excessive tire pressure will blow out rubber valve stems and a hot tire will 
> easily get over 65 psi.  At least with the steel valve stems you have a bit 
> of insurance; you won't blow out the valve stem and have rapid decompression 
> with resulting tire disintegration which in turns shreds the tire and your 
> aluminum trailer body.

It takes only a minute to pause and lay your hand on each of the tires
to see which is heating. More tire pressure means less tires flex and so
less heat from flexing.
> 
> I had all six tires and wheels of my 34' Excella Classic FK trailer removed 
> from the trailer, the 6 *rubber* valve stem replaced with steel ones that 
> use a nut to hold them in place, the tires balanced and remounted for 
> $70.00.  To me, that $70.00 is cheap insurance and it gives me peace of mind 
> knowing that I have greatly reduced the chances of a rapid decompression 
> with the resulting damage to my Airstream.

My flat bed trailer (made from a Monitor) has a couple of those steel
stems. Those tires leak the worst.

> 
> The tires on our Airstream are also rated as ST by the maker as Special 
> Trailer tires made to do the job.  I'm not out to change your mind about 
> what you do.  But for the new trailer owners of either vintage or new 
> Airstreams they need to know that there are other ways to do things.  Those 
> things you can do get down to a personal level, we can all choose for 
> ourselves  how we want to handle these situations.
> 
> I'd still advise people to replace rubber tire stem with steel tire stems 
> due to the built-in safety factor.  At least that's one less thing to worry 
> about and it is one thing we can control.  I'd hate to pay even the 
> deductible of the insurance cost because I tried to save a few bucks when I 
> personally knew better.  Like I said, it's a personal thing and I only 
> posted my personal view.  I'd still advise people to use materials made for 
> the job regardless for their own sake.
> 
 About 35 years ago, my dad built a utility trailer for me using tires
alone for the suspension. So its loaded and then the tires inflated to
just barely hold the load. Trails beautifully when so adjusted. It not
have but one long trip in that time but so far I've not had to change
the very used tires even when I put a half ton of stuff in it.

The old Airstream suspension tends to be stiff. Running the tires with
air pressure just enough to hold up the load lets the tires cushion some
of the road imperfections and so makes the trailer ride smoother. Like
my utility trailer. If we check the tire temperature at hourly intervals
and don't detect a large rise, only running over a broken bottle should
cause the tire to deflate rapidly. And that bottle will cut the fully
inflated tire too.

I think that if the tow vehicle has radial tires, that the trailer tires
must be radial so that the rig stops straight. Radials grip the road so
much better than bias ply tires that the tow vehicle with radials and
trailer with bias ply will lead the trailer to pass the tow vehicle in
every panic stop. State laws don't allow mixing type of tire on the tow
vehicle and I think should not allow mixing tire types in the rig.

Gerald J.