Tire pressure

[ricohman]

Re: Tire pressure

My brand new tandem boat trailer came from the factory with car tires. They lasted for years. The capacity x 4 exceeded the trailer capacity by a reasonable margin.

My new 28 ft trailer came with 4 ST tires. I don't know if a new trailer can legally have anything but where I live.

 

[JimS123]

Re: Tire pressure

Car tires are designed for cars. And are designed to work with a suspension and steering components. Double axle ST tires shrug off tight turns at low speeds and you can leave them "loaded" for lengths of time. Auto tires seem to nearly fold off the bead.
Do that with auto tires and the sidewalls start to come apart. Although I was a kid at sears when I sold tires, I used a lot of what I learned when I became a mechanic.
Just because the load rating matches does not make any auto tire fit for trailer use. People use them and I'm sure lots have no trouble. Trailer tires are designed they way they are for good reason.

A review of the catalog from the year I bought my trailer showed that for any given trailer length they had numerous models with the same frame size and number of axles. The only difference was the type of tire, and / or the size.

In every single case, the trailers that had the lower weight ratings came with P tires. When the rating was above the load capacity of the tire they switches to STs, with a load range B,C, D as required.

I guess they didn't read the manual about trailer tires......LOL.

 

[dazk14]

Re: Tire pressure

Somewhat off topic...but I also didn't read all the posts.
If you want a monster of a great trailer tire in 14" only... Kumho radial 857's are miles ahead of competitors.

These are used extensively in Europe as LT tires. Drop about 110 lbs when running tandem axles. They are also a bit taller, so check clearance.
185R14c - load capacity 1874 lbs Q speed rated - read 99mph speed rated
195R14C- load capacity 2094 lbs R speed rated - read 106mph speed rated
205R14C- load capacity 2271 lbs Q speed rated - read 99mph speed rated

Remember, the load rating is at maximum speed. Incredible capacity and they are loafing running 70mph highway speeds.

 

[bigdee]

Re: Tire pressure

A review of the catalog from the year I bought my trailer showed that for any given trailer length they had numerous models with the same frame size and number of axles. The only difference was the type of tire, and / or the size.

In every single case, the trailers that had the lower weight ratings came with P tires. When the rating was above the load capacity of the tire they switches to STs, with a load range B,C, D as required.

I guess they didn't read the manual about trailer tires......LOL.

Good point. You are absolutely correct, the difference is load capacity.

 

[dazk14]

Re: Tire pressure

A review of the catalog from the year I bought my trailer showed that for any given trailer length they had numerous models with the same frame size and number of axles. The only difference was the type of tire, and / or the size.

In every single case, the trailers that had the lower weight ratings came with P tires. When the rating was above the load capacity of the tire they switches to STs, with a load range B,C, D as required.

I guess they didn't read the manual about trailer tires......LOL.

Jim has this correct!! Passenger tires will work, less 10%. Somebody shoot me, I'm sucked into a trailer tire train wreck conversation.:doh:

A dozen+ years back a local tire Dealer was offering 13 and 14inch tires, mounted for $99 as a loss leader. If I recall...Of course it was like a 165/80 tire that nearly no car used, but 80 series have great load carrying capacity....

After I sent the 15th trailer through, their Marketing plan changed.

Yes, the sidewalls flexed more than a trailer tire, but given that most leaf springs rust solid in short order, the boats were very content and I know many of those tires are still in service.

 

[crackedglass]

Re: Tire pressure

The issue I run into is that my boat is 111lbs, maybe 150 loaded tops. The trailer has a GVW of 750 lbs, its the lightest model I could find for a 14' boat without going down to 8" wheels. With 4.80x12 tires, which ask for a Max pressure of 60psi, the trailer bounces all over the road, I think its off the ground more than its on the road.
I don't have a passenger tire option in 12", and I can't get a softer or lower rated tire. The boat doesn't even compress the springs, it never will. The tires are the only suspension and I've run mine at 30 psi for years, and even at that pressure I get far more wear on the center tread than on the outer edges. I just replaced the original tires from 1991 due to sidewall cracking. If I put 60psi in these, I might as well tow it without springs.
The old trailer had 8" wheels and it was worse since the small tires took the bumps worse.

The only trailer tire failure or blowout I've had was due to overloading, not tire pressure. I had about double the weight on a small trailer on the open highway. One tire gave out after running 800 miles at highway speeds with almost double the rated load on it.

 

[naturelover]

Re: Tire pressure

The issue I run into is that my boat is 111lbs, maybe 150 loaded tops. The trailer has a GVW of 750 lbs, its the lightest model I could find for a 14' boat without going down to 8" wheels. With 4.80x12 tires, which ask for a Max pressure of 60psi, the trailer bounces all over the road, I think its off the ground more than its on the road.
I don't have a passenger tire option in 12", and I can't get a softer or lower rated tire. The boat doesn't even compress the springs, it never will. The tires are the only suspension and I've run mine at 30 psi for years, and even at that pressure I get far more wear on the center tread than on the outer edges. I just replaced the original tires from 1991 due to sidewall cracking. If I put 60psi in these, I might as well tow it without springs.
The old trailer had 8" wheels and it was worse since the small tires took the bumps worse.

The only trailer tire failure or blowout I've had was due to overloading, not tire pressure. I had about double the weight on a small trailer on the open highway. One tire gave out after running 800 miles at highway speeds with almost double the rated load on it.

I have the same problem with my 12' jon. I have the little 4.80x8's, and they don't flex, even at 30psi. I could run them flat and never know it I think. I'm leaning to trying to around 20psi or so to see if it helps, the poor boat takes a beating.

I've been thinking about taking a spring leaf out and making it a one spring trailer, but I still don't think it would ever compress it, just not enough weight.

 

[bigdee]

Re: Tire pressure

I have the same problem with my 12' jon. I have the little 4.80x8's, and they don't flex, even at 30psi. I could run them flat and never know it I think. I'm leaning to trying to around 20psi or so to see if it helps, the poor boat takes a beating.

I've been thinking about taking a spring leaf out and making it a one spring trailer, but I still don't think it would ever compress it, just not enough weight.

THEY ARE NOT SUPPOSED TO FLEX. Trailers ride rough and bounce without a load, that is just the way it is. Spring travel and shock absorbers are the only possible cure. Tie everything down...the boat will survive.

 

[lckstckn2smknbrls]

Re: Tire pressure

I have the same problem with my 12' jon. I have the little 4.80x8's, and they don't flex, even at 30psi. I could run them flat and never know it I think. I'm leaning to trying to around 20psi or so to see if it helps, the poor boat takes a beating.

I've been thinking about taking a spring leaf out and making it a one spring trailer, but I still don't think it would ever compress it, just not enough weight.

The trailer I bought for my 1436 jon started out with a single leaf springs and load range A tires but I changed them out for 3 leaf springs and B tires. Give it a try.

 

[ondarvr]

Re: Tire pressure

Even the tire manufactures say it's OK to run passenger car tires on a trailer if they meet the load rating, and passenger car tires meet a stricter set of spec's than trailer tires do. I've run both and never had many problems, but passenger car tires do last longer. Go with LT tires if you need a higher load rating.

 

[ricohman]

Re: Tire pressure

Even the tire manufactures say it's OK to run passenger car tires on a trailer if they meet the load rating, and passenger car tires meet a stricter set of spec's than trailer tires do. I've run both and never had many problems, but passenger car tires do last longer. Go with LT tires if you need a higher load rating.

Yes they say you can use them but you should be subtracting 10% of the max load of any P tire used on a trailer. This is according to the manufacturers.
Also, using P tires on heavy trailers is one of the main causes of sway, as the sidewalls flex. P tires are designed for braking forces and acceleration and comfort. So they flex so much more.
However you can use an LT tire to its max rating on a trailer.
If your load is light I'm sure the P tires would survive. I wouldn't use them on my 28ft boat trailer or my car hauler though.

 

[bruceb58]

Re: Tire pressure

They don't make a P tire that has a high enough capacity for a heavy trailer. Find a 14" passenger tire that has enough capacity for a tandem 7000# trailer!

 

[smokeonthewater]

Re: Tire pressure

Soooooooooo

WHO was it again that asked anything about passenger tires?????

Seems to me that the O/P asked about tire PRESSURE....... Jus sayin......

 

[bruceb58]

Re: Tire pressure

Soooooooooo

WHO was it again that asked anything about passenger tires?????

Seems to me that the O/P asked about tire PRESSURE....... Jus sayin......

Yeah but there is always someone with passenger tires on their trailer that seems to want to bring it up for some reason. Surprised Doel Fins weren't brought up!

 

[dazk14]

Re: Tire pressure

Yeah but there is always someone with passenger tires on their trailer that seems to want to bring it up for some reason. Surprised Doel Fins weren't brought up!

It doesn't matter what tires you are running...as long as you're using Mobil 1 oil in the tow vehicle and Pennzoil synthetic in your 2 stroke.:deadhorse:

There...I just completed the circle of insanity and it only took 55 posts to get there. Somebody shoot me.:rip:

 

[ondarvr]

Re: Tire pressure

Subjects frequently get changed to a new direction when a different solution to the problem is suggested, then the debate continues in the new direction. Sorting through threads like this can be very enjoyable, entertaining and educating. Much of what's posted is feelings and hear-say, not fact, you need to toss that stuff out and go to the facts, which typically don't line up well with the "feelings and hear-say" replies.

I'll point to the last few responses as another change in direction.