Com-Pac Yacht Owners Association

  i planning on moving up to 12" tires on my cp16 trailer. i figure i need at least a c rating but i wonder about size should i go with 480 or 530. what is the difference in tire height? i already have the wheels (8 bucks a piece). also should i go with radials or bias?

I believe the number is the width of the tire. I just put on new tires this spring on a cp16 Hutch trailer, they are 5.70-8, load range c, 910 lbs at 75 psi. Four ply side wall and 4 ply tread. I believe the originals were load range B, a little light for that rig.  Got them from FS about 45 bucks each mounted. they were supposed to order 6 ply but only had the 4 when I showed up. It was a $2 difference. One guy in the garage said they didn't make a six ply (not sure I believe that, he blamed the mix-up on the lady in at the counter with a "she is a woman what do you expect"- then when I went to grease the hubs noticed they had put two different sized lug nuts on-I always forget why I don't shop there...). Anyway, Make sure you have room between the tire and the frame for width. Fenders can be moved but you are stuck with width. If it were me, I would pull the trailer to where I was buying the tires and let them size them. Also,they will look at you funny but you can get them balanced, which I don't think is a bad idea. Though I did not opt for this on my recent purchase I have on the heavier trailers on other boats I have had.  I believe the radial is going to have a softer sidewall, they may not even make a radial in that size.  If you can get a ST or "Special Trailer" that may be the best approach if long hauls are in your future. Best of luck.

   thanks for the quick reply.

After a lot of research I am replacing my 570-8 C Bias(5 hole) with 480-12 6Ply Bias(5 hole).................no problem with fenders and width , but the tire size increases overall height 3 inches ( 1 1/2 inches from axel center to top of tire)   and  I may have to move the fenders up................................nies

Load rating.
The only thing that counts regardless of diameter.
Radials if you can find them.
Larger wheels for brakes if needed.
How much weight are you hauling with a CP-16.

Now a note about contact surface ... remember 'wide Ovals' radials, belted tires?
Hot Rod Magazine did a story that had circles, and arrows, and pictures indicating
that a wide tire had a wide but less long, read, narrow contact surface while a narrow tire had a
narrow but longer contact surface.
Their conclusion was both tires had the SAME amount of rubber on the road.

Tire America.com will have all the size and load and heat-traction-wear data on any size tire.

My Carlyles have been rolling fine since 1996.

skip.

    since first posting my question about 12" trailer tires i have been doing some internet research, trying to get a handle on which tire i should buy. it seems that every review i have read regarding ther following brands was unfavorable---goodyear marathons, nanco, towmaster, nankang, and carlyle. most of the reviewers complained about blowouts, poorwear and even damage to their trailers. can anyone here recommend a brand of tire i can live with. this is for my cp16 so i figure i should have a load c at least.

steve,

i have carlyles on my trailer and haven't had a problem with them

carl

   thanks buddy

Not that anybody will be doing this ... but just for poops and grins lets consider bolting on a pair of mobile home leaf springs, hubs, rims, wheels and tires.

I can't think of a set up that can carry and handle any more weight then these babies for their size. And these axels are fitted with electric brakes, which I never hooked up.

Unbelievable these guys handle 7,000 lb per axle.

In 1984 my 16 foot double axle trailer was made from old rusty scrap farmer steel and two shortened 7,000 axles with mobile home wheels.
I hauled a 12,000 lb abandoned batch bake oven out of Detroit to Sylvania, Ohio on it for rebuild and resale.

skip.  

Hi kickingbug1,

    Did you have a problem with your 8 in tires; is that why you want to go with a 12 inch tire?  I bought some new tires for my trailer a couple of years ago.  I upgraded from 5.7-8 4pl load range b (715lbs per tire) bias tire to load range c 6 pl (910lbs per tire).  The brand name is Loadstar and I have not had any problems with these tires, they work great.  If you have a lot of stuff on your boat and you want a higher rating you can get a load range d that is (1075 lbs per tire).

Hi Mattman,

   It is interesting that they said your tire is 4 pl because if your tire says load range c (910lbs) 75psi, it should be 6pl.  Each tire should have a PR_ (ply rating on the tire).  Mine has a PR6 on the tire.

    Hope this information helps.

    Brian

Just to be clear. Are we talking lb per axle or lb per rubber tire-which is the load range embossed on the tire's side wall a x amount of inflation?

"... from 5.7-8 4pl load range b (715lbs per axle) bias tire to load range c 6 pl (910lbs per axle). "

"Per axle? or per tire?"
The 7,000 lb axle refers to the tubes, saddles, U-bolts, springs, equalizers, spindles, bearings, hubs, lugs and rims ... regardless of rubber tires.

The most stress is placed on the spindles and bearing when turning at speed. If your going to break something it's during a turn.

skip.

Thanks Brian, I knew what you meant. Just poking you a bit.

Skip,

     Thanks for catching my mistake.  I should of said per tire. 

i have checked and found that 480 12inch tires are 20 inches tall and 530s about and inch or so higher as well as wider (little over 5 inches). for those of you using 12 inchers, is there a big difference in stability while trailering with either size?

Brian, the tires do say 4 ply on the sidewall. Who knows, they are doing ok for the trips I am making. Warm but not hot to the touch. They were only going to inflate to 35 psi but I told them I wanted the 75. the mechanic said that would be too rough a ride for the trailer and we settled on 50. I have not noticed any problems but will increase now that the weather is cooling down. I have always run my tires at max pressure before. Just my best guess.

Trailer tires should always be set at the reccomended pressure, if it says 50, do 50, 75 do 75,

The reason is the sidewalls need to be full, and lower pressures could cause a premature degradation and destruction of the sidewalls leading to failure early on....... Atleast that is what I was told by my trailer company buddy that has been dealing with trailers for about 30 years..... around here he is the go to guy..

I always keep mine at 90. that is what they want, so that is what they get.

Car tires are a different story. My truck recommends 32. the tires say 50. I run at 40 and got a better ride. I beleive they are more adjustable as far as tire pressures, otherwise when mudding why would you decrease tire pressure....... or rock crawling, why run 3 to 5 then?

Just my thoughts.
Mac

Mac:
   Aren't those numbers on the tires maximum pressures? I play around with my Tundra pressures depending on if I'm towing my construction trailer or not. I've found I can increase the tire life that way. But I'm nowhere near 50 psi.
   My 23 trailer tires get 50-55 but I've  so little mileage on them that it is impossible to tell if they are wearing correctly. But your "sidewalls needing to be full" arguement makes sense. 
   90! I'd be scared putting that much pressure in any tire, old or new. My fear probably stems back to my wayward youth when I blew up a bike tire at the gas station. My ears rang for days! Funny how you remember wierd stuff from the days of yesteryear!
   Remember that the pressure increases on the road when the tires get warm.
Bob23..checking my trailers tires and pressure.

Bob - I routinely run 90 psi. The contact patch is very small on our trailer tires compared to a car or truck tire, so the pressure must be high. With about 3000 lbs of weight, that's 1500 per tire. If the contact area is 4"x4" or 16 sq. in., you need almost 94 psi (hypothetical example). If you underinflate, the patch gets bigger and the heat from friction increases, as does deformation of the sidewall.

Obviously larger tires have bigger contact patches, so need less air pressure to support the same weight. Mine are hilariously small - it seems like a miracle that those little tires can carry that load. But it's been three years of towing and so far no problems.

Wes

Quote from: kickingbug1 on September 11, 2013, 02:21:21 PM
    since first posting my question about 12" trailer tires i have been doing some internet research, trying to get a handle on which tire i should buy. it seems that every review i have read regarding ther following brands was unfavorable---goodyear marathons, nanco, towmaster, nankang, and carlyle. most of the reviewers complained about blowouts, poorwear and even damage to their trailers. can anyone here recommend a brand of tire i can live with. this is for my cp16 so i figure i should have a load c at least.

Kind of late, just saw this.  I've got a little over 8 years but probably only about 3500 miles on the original set of Trail America ST bias ply tires.  They are just now getting enough sidewall cracking that I'm considering changing them. 

Thanks, Wes.
   I stand corrected...I'm always amazed about the things I learn here on the site! Makes sense...my road bike tires ride on about 110 psi.
Bob23

Quote from: Bob23 on September 18, 2013, 04:48:04 AM
Mac:
   Aren't those numbers on the tires maximum pressures? I play around with my Tundra pressures depending on if I'm towing my construction trailer or not. I've found I can increase the tire life that way. But I'm nowhere near 50 psi.
   My 23 trailer tires get 50-55 but I've  so little mileage on them that it is impossible to tell if they are wearing correctly. But your "sidewalls needing to be full" arguement makes sense. 
   90! I'd be scared putting that much pressure in any tire, old or new. My fear probably stems back to my wayward youth when I blew up a bike tire at the gas station. My ears rang for days! Funny how you remember wierd stuff from the days of yesteryear!
   Remember that the pressure increases on the road when the tires get warm.
Bob23..checking my trailers tires and pressure.

Higher pressures are interesting when filling them up, and will definitely cause you to find the flaws easier! LOL
Lower than the recommended will cause more heat buildup and then in turn cause more premature wear. Also (I have heard) that the sidewalls on trailer tires are stronger so by underinflating them they buckle which can cause them to also break apart.
The whole thing about tires is also so interesting......... Everytime I see about people having tires from over 10 years ago or see people come into the marina with deep cracks (mimic-ing the eczema on my hands at its worst) I wonder why I had a perfectly good tire blow on my trailer when I first went and picked the boat up.......

Mac

   just in case anyone wanted to know. i put 5.70 12s on my cp 16 trailer (majic tilt) with no problems. i did have to raise the fenders a bit but that was easy. just unbolt them from the frame and move them as high as the brackets allow and drill two new holes. i havent tried it on the ramp yet but i did pull it down the highway at 70 mph with no problems.

The tire size on my org. trailer was 570-8 C and what I have replaced over the years, was told at Farm & Fleet the next size up was 480-12 6 ply ,both are Bias, now I wonder if true..........................any tire guys out there?.........nies

   worked great on the ramp----i didnt notice any difference