Flat tire on haul-out today . . .

tpenfield

tpenfield

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Yes, someone letting the air out . . . another possibility. I had a situation with my car a few weeks ago parked in a parking lot over night. The left rear tire was down about 10 psi. I figured it was a nail or something. But upon re-inflating the tire, it has stayed at the inflation psi for weeks. So, probably a nefarious act.
 
tpenfield

tpenfield

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This trailer incident has got me thinking about the balance point on the trailer. . . .

According to the Mfg spec./drawing the balance point of the boat is 104" forward of the transom keel.
Trailer-Specs-1.png
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I measured that point on the trailer . . .
Trailer-CoG-2.jpg
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It puts it at the rear edge of the front tire. I assume the trailer's balance point will only make the overall balance point even more forward. My thinking is that the balance point loaded should be over the middle wheel +/-.

In this picture, the boat is all the way forward snugly in the cow-catcher and the bunks stop right at the transom. So, position-wise the boat is where the trailer intends it to be. Just not sure about the balance point? The center axle is about 17" behind the boat's balance point. . . . and might be 20" behind the total balance point.

Thoughts?:unsure:
 
A

airshot

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I have found buried nails and screws in tires that only leaked when the tire was in a certain position. Have had them not leak for two weeks then leak down in two days, after time I found the buried nail....odd things do and can happen..
 
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Pmt133

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Most commercial trailers have axles further back. I would assume the balance point to be set where it needs to be to maintain an appropriate and reasonable tongue weight. Probably something like 60/40. 60% in front the axles and 40% behind. Seems to always end up being that way when I load the trailers up anyway...

I would think if you put the balance point over the center axle you would have too little or almost no tongue weight no?
 
tpenfield

tpenfield

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Yes, in my reading on tri-axle trailers, the weight should be a little bit forward, which makes sense. It just seems quite a bit forward, but maybe it is OK. In terms of a 60/40 split, I assume it would be referenced to the center axle.

Last time I measured the tongue weight it was 1,260 lbs, so the weight on the wheels would be 12,340. 60% would be 7,404 and the remainder would be 4,936.

With a few measurements, I could probably calculate the balance point.
 
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Pmt133

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I would say that's probably about right. I always referenced it to centerline of the axles... in your case the middle axle. (Our work trailers are all double). For simplicity sake, I'd guess you're just ahead of the centerline of the front axle. Being your tongue weight seems in line I'd say its about right.
 
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Mc Tool

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Not a boat but my Mrs arived home one day with a dead flat tire , she claimed to have no knowledge of this ( she has a track record of just heading home and hoping for the best........so bulls hit 😃 ) anyhow there was a 8 inch coach bolt in the tire , I could see the head but the other end had actually beaten a hole in the ally rim between two spokes ............again she claims that there were no symptoms. To be fair I didnt see the 3 inches of threaded bolt end poking out thru the rim next to the valve stem on the 1st look .:):)
 
tpenfield

tpenfield

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Mc Tool said:
Not a boat but my Mrs arived home one day with a dead flat tire , she claimed to have no knowledge of this ( she has a track record of just heading home and hoping for the best........so bulls hit 😃 ) anyhow there was a 8 inch coach bolt in the tire , I could see the head but the other end had actually beaten a hole in the ally rim between two spokes ............again she claims that there were no symptoms. To be fair I didnt see the 3 inches of threaded bolt end poking out thru the rim next to the valve stem on the 1st look .:):)
Click to expand...
OMG . . . surprised she made it home.
 
Lou C

Lou C

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Wow all this make you realize that a TPMS system for trailers could be a really good idea! That pic of the tire on Scott's trailer is why I still use bias ply tires, yes they don't last as long but on a trailer they usually will dry rot before the tread wears out, long before actually. No steel belts to delaminate/cause damage/or corrode on a salt water trailer.
I've been using Kenda Load Star bias tires (225/75-15 load range E) for a long time with no failures not even a flat!
 
tpenfield

tpenfield

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I took some measurements and this is what I came up with for balance point (referenced from the center axle)
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13,600 lbs. total Weight . . .
Trailer-Weight-2.png
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So the balance point looks to be right over the forward axle.

Tongue weight is 9%.
 
Scott Danforth

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Lou C said:
Wow all this make you realize that a TPMS system for trailers could be a really good idea!
Click to expand...
the shimmy and spray of rubber told me I lost a tire. probably faster than the TPMS would have indicated. just 3/4 hour prior I had checked the tire pressures prior to leaving the camp ground.
 
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Pmt133

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Mine are speed rated 81 I think.

That looks about where I'd expect the center of mass to be. More like an 80/20 split but lets face it... boats are a different animal and hard to get tongue weight with. I think you're fine.

Could always see where the trailer manufacturer wants the CM.
 
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Jeff J

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All tires have speed ratings and sometimes they are lower than a person would think, especially if a person only looks at size and price when buying. Speed ratings and load capacity could be more important than size.

I have seen recommended maximum speeds for towing on trailers. Check the trailer owners manual or the speed rating on the tires. You might find out 55 or 65 mph was supposed to be the max speed.
 
Scott Danforth

Scott Danforth

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M rated trailer tires. 81mph. although only D load rating (8 ply). Next set will be Q-rated trailer tires (99mph) with an E load rating (10 ply)
 
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cyclops222

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I was doing interstate traffic speed. BANG !! we hit a road problem where the lane pavement was lower than the bridge pavement. I thought the front end and tire were damaged for sure. Checked at a dealer nearby. No damage.
Changed tires to just below the maximum rated.
 
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