trailer tire size survey

[whitecap]

Hello, I have 5.30-12 tires on my magic-tilt railer.  I've seen pictures of other cp16's that look like there is a smaller size tire installed.  I'm interested in going with a smaller size to make launching & retriving easier (even a few inches is gonna help).  I'd be interested to know how small the manufacturer may have gone & also if some of you guys with the little tires have trailered over long distances at high speed with no trouble.  -thanks for the input

[kickingbug1]

    i wouldnt go smaller. i have 8 inchers and have had no problems with bearings but im considering12s or even 13s for mine next year. hell ill trade if you want.

[CaptRon28]

The Magic Tilt tandem axle trailer under my Horizon has 10 inch wheels. I figure that these wheels are doing about twice the revolutions as the 20 inch wheels on the Chevy Avalanche that is towing it. Truck's doing about 60 mph, trailer is doing the equivalent of 120+. Note that this will effect both bearing and tire wear. I can probably live with that, but I'm not at all happy with the tiny drum brakes behind each wheel. Smallest wheel that will supprt disc brakes is 13 inch, although there are two manufacturers that have smaller discs that will supposedly work with the 10 inch wheels. I bought a set of the Kodiac's and they do NOT fit the 10 inch Magic Tilt supplied wheels. Next season I plan on upgrading to 13 inch wheels and TieDown Engineering ventilated discs.

Disc brakes are a no brainer to me. Main reason is salt water and how they effect the nearly sealed drums. If you can't flush it out immediately after launch or retrievel, the salt WILL damage the brakes, guarenteed. The wide open discs will just dry off in seconds. Add better stopping power, faster cooling down, and no need to ever adjust them.

Anyone wanting to go to much smaller wheels should possibly rethink this strategy.

[skip1930]

Yep the disc brake pads are at all times in light contact with the discs. The heat of friction keeps things dry and clean.
What actuates the pistons in the calipers? Surge or Electrical magnetics?
Don't know a thing about what fits and doesn't fit.
I have 10" dia with well greased bearings. No brakes.

skip.

[CaptRon28]

Skip - Agreed that there is light contact between the pads and rotor, but there is not much heat generated. I usually find it's about 10 degrees greater than the air temperature. The open design of the rotor, especially if it's one of the ventilated versions (two surfaces separated by cooling slots) actually helps to cool things down a lot. Drums heat up fast and lose heat very slowly. That's why they tend to fade when used a lot, like downhill on a mountain grade. I've measured trailer drum hubs at well over 300 degrees F after a 5 minute rest period. Never had a disc system  register over 125 after a 5 minute cool down. But the best thing is that they shed water even quicker that the heat. Salt water won't sit inside the drum causing all sort of long range problems. They're also self adjusting. How many of you actually adjust your drum brakes at least once a year?

No brakes is not an option in most states if the trailer weighs over 2,000 or 3,000 pounds, depending on the state. My 20 foot Horizon and Magic Tilt trailer come in at around 4400 pounds, which technically calls for brakes on all wheels.

They make both electrical and hydraulic versions of both systems, with one variation that even has both. The hydraulic or surge version works by allowing the master cylinder piston rod to push back when the trailer stops. The tongue has a built in slide that causes this. Most electrics use a truck mounted programmable brake controller that senses deceleration and applies voltage. I'd prefer electric, but making them waterproof is a major issue and most boat trailers wind up with surge based hydraulic  brakes. I've got 5 trailers - the 3 that carry boats are surge and the 2 car haulers are electric.

[Citroen/Dave]

After rebuilding the disk brakes on both renditions of the DS Citroen, the earlier had two pistons on one side with a floating caliper and the latter had opposing pistons on a fixed caliper, I finally figured what pulled the pads back when the brake pedal was released. It is the distortion of the "O" rings.  The round cross section is pulled to an oval when the brakes are applied and the rubber tries to return to a round shape when the brakes are released.  Self adjustment is accomplished when the piston actually exceeds this "ovalization".  Square cross section "O" rings respond in a similar fashion.

[skip1930]

When building our SCCA, A-Sports Racer, an A-H 100~6, into a fire breathing Ford 289 HiPo with T-10 the rotors were fitted with front caliper Kelsey-Hayes four puck units with Mintex pads...the back calipers were Kelsey-Hayes two puck units with a proportioning valve and Mintex pads. All flexible brake lines were Aeroquip so no squish in the pedal. Raced on a new set of pads, practiced on the old race pads, new for the next race. Ed Pink built the 9 inch pumpkin and it needed the half shafts out of a Corvair to survive to twisty efforts. The moment of torque and the moment of bend.

So much fun...skip. Come to think of it our single axle race car trailer never had brakes either.

[MKBLK]

Whitecap - Having recently brought my newly acquired CP16 down from Groton, CT to Levittown, PA (~ 200 miles) and two round trips to Barnegat Bay (Bayville, NJ - ~120 miles); I (knock wood) have not had any problems with my 8" wheels. Of course they do look rather small and spin like the devil at highway speeds, but seem to be just fine for 16 footers which weigh about 1200 lbs. plus gear and trailer. I would think that Hutchins and Magic-Tilt knew what they were doing when they specified 8" wheels for the CP16.

Marty K.

[CaptRon28]

Marty -

8 inch wheels would work, but just note that the bearings and tires will probably wear out a lot faster. And you may have to keep the speed down a drop as well - they could overheat at 60+ mph. Most of the heat comes from the tire distorting a drop as the flatter contact patch moves around the tire much faster than your car or truck tires. That could be the equivalent of running the 30 inch tires on my truck at maybe 180 mph.

[MKBLK]

CaptnRon28 - I agree that at highway speeds of 60+ overheating could be an issue. I've made it a habit to pretty much stay in the right lane and hold at 55. Also, I would stop every 75 - 100 miles to check the wheel bearings... and stretch my legs! Being a sailboat sailor, I'm learning that I don't need to check my watch all the time. So, should Skip be reading this post, just how many rpm are those little 8" buggers going at 55 mph? Or 65? Scary, huh?

As previously reported, my longest trip so far has been about 200 miles with two stops to check wheel bearings. My next outing (this coming weekend) will be a bit different. The 200 mile trip was from Groton, CT to Levittown, PA. Pretty flat 99 percent of the time. My other trips down to Barnegat Bay were also flat. Sunday, I plan on sailing lake Nockamixon in Upper Bucks County, PA. The roads to Nockamixon look like a rug someone pushed up from one side. No overdrive on this trip! Probably plenty of driving in 2nd gear. We'll see.

Marty K.

[skip1930]

" So, should Skip be reading this post, just how many rpm are those little 8" buggers going at 55 mph? Or 65? Scary, huh? "

skip here, more rpm's then the toe vehicles wheels? Sure. Scary? No not really. I figure that the tire engineers who designed the tire carcass for the weight to be handled and the rpm to be encountered at high way speeds felt that they made all the right decisions when choosing the design for that smaller rim diameter.

I believe that the answer is molded right on the side wall of the tires. Somewhere it says, " LOAD RATING AT XX LB " and that is a might more important then rpm's. Don't exceed the rating.  

If you go to TIRE AMERICA on line and look~see the outer diameter of the smaller trailer tire and the outer diameter of the truck tire a comparison can be made in rpm's per mile per hour. Actually I think TIRE AMERICA has such a chart.

skip.

[MKBLK]

Just for fun, I checked the tire size chart at Discounttire.com and came up with the following -

At 55mph an 8" wheel (hub) is going about 166mph (compared to a 15" hub)
At 65mph an 8" wheel (hub) is going about 197mph (compared to a 15" hub)

But, I agree with Skip, these tires are designed for high rpm's and as long as they are kept at their proper psi and aren't overloaded, they ought to last many years. I read somewhere that the tire walls will probably wear out before the tread, so keep an eye on sidewall condition and psi.

Next time you're landing in a jumbo jet, just think of the huge weight upon contact with the tarmac and the landing speed about 160 knots or so!

Marty K.

[makedevine]

I do not have a problem with running a smaller tire , but with a larger tire you"ll slow down the speed at witch the bearings are spinning lowering the chance of failure. And the induced drag of a smaller tire compared to a larger one. Give me a taller tire any day. Have trailer will travel!!

[CaptRon28]

In my opnion, the main disadvantage of smaller tires is that they rotate maybe 2 or 3 time faster than the tow vehicles tires. That means that the flat spot touching the asphalt is also moving at 2 or 3 times the rate. This flex increases heat build-up in the tires, and heat causes most failures on the road. Other objections include the fact that you can't put disc brakes behind these tires and using drum brakes in salt water is a recipe for eventual brake failure, and the bearings are doing 2 or 3 times the job they should be doing.

That said, I expect to keep the 10 inch wheels on the MagicTilt under my Horizon. But note that I expect to never have to tow this rig more than about 10 miles at lower speeds (less that 55 mph). Anything else would get me to spring for 13 inch wheels with 4 disc brakes.

[Salty19]

I agree these tires are designed for high RPM's.  But you do have to keep them inflated.  Cracked sideways is what you look for. Any cracks are bad. And the "E" load rated tires are best, but I think the "D" rated ones will work on a CP16.
I've traveled several hundred (400) miles one way on 8" and 10" (CP16), and now 12" (CP19).  The keys are the right load rating, keeping speed down to around 60 (occasionally will go a little faster), inflation at max pressure and stop to check and let them cool on long trips for about 10 minutes.  On hot pavement, they seem to be very warm but cool enough to leave your hand on the hubs and tires. A good time to check over everything and let your cars transmission cool down (leave the engine running).

Tires that are old or unknown age or load rating should be suspect.