Confirmation of Tyre Pressure for Boat Trailer

[Splash]

Good morning all!

Glad to be sitting up after a hellish night vomiting and diareha (sp?). :'(

I want to clarify and confirm how much pressure I should be putting into my boat trailer tyres..

Here are the tyre specs:
Light truck tyre
Hankook radial RA08 tubeless
175R 13C 97/950
65 psi max


Should I be pumping 65psi into these tyres?

Thanks people

Splash

[backlash08]

is there a tyre placard on the trailer?
the tyre would also have a max pressure inflation rating on the sidewall

but 65psi doesnt seam too high for a boat trailer

cheers - Craig

[Splash]

thanks Craig

[liltuffy]

I run 50 psi all the time in a similar tyre holding up my Vsea

[GBC]

ditto - tandem mackay on 14" LT's

[Roughasguts]

I have 55 psi holding up me caravan and thats 1900 kg so I would think somewhere under that but over 45 Psi.

I think with light truck tyres you put in just enough air, so theres no side bulge in the tyres.

[STUIE63]

i always pumped up the tyres till there was 2 psi difference between the cold and hot pressures
Stuie

[whiteman]

Mine are at 55 normally but will put in 60 on a longer trip.

[tenzing]

Splash I am no expert, but I am fairly sure that the tyre pressure will be proportional to the load .
So if your BMT weight is say 75 % of the max load of the 4 tyres combined then your pressure will be about 75% of max . That would be closer to 50 psi.
I run mine at 55 psi by the same reasoning.( 185R14 LT - BMT 2500kg)
Brendan

[Splash]

good points everyone.

thank you.

[trueblue]

I run mine pretty close to max, to make sure the tandom steers better when reversing it around corners.

[PWCDad]

There is a very good old rule of thumb that works very well for working out the ideal pressure to run a tyre.

I've used it for my little Subaru sprint car to my F250 Crew Cab and the 3500kg off road caravan it towed. Van and truck sold now and gone back to the sea!!!

Its the well used 4 psi rule.

That is ... for any given load on a tyre up to its maximum load and pressure rating the pressure from cold to hot should be 4 psi.

It the tyre is under-inflated heat will build and make the pressure difference over the 4 psi... if the tyre is over-inflated the pressure wont build to the 4 psi.

I usually start at 85% of the tyres nominal pressure rating and work from there.

I take pressure readings on the side of the road after 45 mins running. Its a pain to get right the first time you set up or purchase a trailer but worth it when you get it set. Obviously ... if the load changes significantly you adjust it again.

Not a real concern if a short run to the ramp but I travel an hour each way to my usual ramp, at highway speed.

As a side note .... when running all day with the effie and van or a boat running up the coast to whitsundays et cetera I used a infared temp gun, the point and shoot ones. When we pulled in for fuel I fuelled up and the missus went round and measured the temps of the 8 tyres and 4 hubs of the van. Any temps over 50-55 deg c was cause for further investigation of the tyre pressure or the hub.

All this was done to avoid a blow out at speed with a rig at 7tons, it was very quick with the gun verses feeling each tyre and hub by hand and the error that may come with the feel method.

I still use the 4 psi rule for my current boat and the Cruiser that tows it.

Regards
Anthony

[Splash]

Thanks Anthony.

The 4psi soudns good to me...

I have now inflated these tyres to 55psi (85% of the nominal 65psi).


Splash

[oldboot]

The 4 psi rule aside.......this all depends on how heavy the boat/ trailer is, in relationship to the tyres.

Ive run light truck tyres up at the maximum 65psi... and that is approprate when running the tyre near its load limit.

But running the tyres too hard can make the ride rough, whick take its toll on trailer and boat.

For instance big doug.. has a little tinny on a little trailer...if he pumps the tyres up past 20psi......it just about bounces off the road.

how do the tyres look under load, do the seem to squirm or bounce too much.
There is no right answer, without knowing the boat and trailer.

cheers

[Splash]

i actually removed both wheels off rig and took them to the servo for air - turns out they had 22psi each.. not good.

i do not know whether the truck man deflated these tyres to transport the boat / trailer down to Adealide or whether they have been like this for a while - Yes I know - pretty slack on my part.

Splash

[dnej]

As oldboot says, if you go too high, you get way too much bounce in some cases. I would recommend a cheap option to check your tyres at home ,cold, is to use one of those 12 volt pumps, (if you cant go to an elcheepo 240 volt one )
They are a bit slow, but work well.
Also a handy back up on the road.
David

[Splash]

thanks dnej

[BilgeBoy]

My father in law has a 34 footer that sits on a custom made I beam trailer with tandem axles. I remember the first time I ever saw it....I said "Hey all ya tyres are flat". To that he just laughed and said..."They cant be, there's 85 psi in em".

He tells me its like a 303 going off when one blows :o :o I think they are 9 ply tyres he runs.

That is one heavy sucker of a boat! Oh...he tells me he will put in a tripple axle next trailer build!


Regards

BilgeBoy

[marty+jojo]

Crap, i only run 30PSI in mine... it seems ok, no probs after 6 years. I have a 4.2mtr tinny with full floors, battery, electric motor, 40hp outboard. Should i run more PSI???
Marty.

[dnej]

Marty,
The whole issue is a relative one.For example, my boat, trailer,motor ,plus gear come up to around 1500kg.

Its correctly balanced on the ball,weight wise,but if I run my tyres at 65psi,which is recmmended,the bloody thing bounces.
I run mine at 50psi, and that is great for me.Little to no bounce.
Check your tyres at home. when cold, then drive down the road to a garage, and recheck them, and see if they have increased very much in pressure.
That will give you an idea.
David

[Moonlighter]

Hi again Splash

Its a very good question you've asked and one that I've asked on several occasions too. Some tyre dealers have no idea about this stuff, others are very good.

I'm about to put some new Yokohama LT 13 inch tyres on my boat trailer, and so I e-mailed Yokohama and asked them what pressure I should run for local trips and also on long runs on the highway.

They needed to know the weight all up of the trailer and the number of axcels.

They recommended for my boat, 50psi around town and 55 psi on long runs or when heavily loaded. The max pressure rated for the tyres is 65psi and my boat weighs about 85% of the tyres max load carrying capacity.

So the advice that others have offered re assessing the weight of your boat/vs tyre load carrying capacity is pretty close.

Cheers

ML