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Trailer and tire size question

Mar 27, 2012
312
Seaward Fox Washougal WA
Hi all, I am looking to down size to a trailer size as my last post indicates. I am real interested in a 20' and it has a single axle with really small wheels and tires. I have read that long trips should have a double axle. Will this trip really limit my exploring to short local trips? If so, what is the recommended max travel range for these little trailers?
 
May 24, 2004
6,769
CC 30 South Florida
The requirement for twin axles is for load carrying capacity. If the boat weighs under 4,000# it will be fine with a single axle. Now small tires do not have the load bearing capacity of larger diameter tires and they tend to heat up quicker. Add the weight of the boat to the weight of the trailer and subtract the approx. 350 lbs being carried at the tongue and divide the remaining weigh by 2. That will be the load to be carried by each tire. The tires should be rated for the weight load plus a 20% safety factor to handle road conditions which may cause momentary increases in weight forces.
 
Nov 9, 2008
1,338
Pearson-O'Day 290 Portland Maine
Biggie,

be sure what your axel can take. There is more than one kind of single axle. Some take 2000 lbs, some take 3700 lbs, and some can go as high as 6000 lbs. With small tires, I would assume a small load capacity. Other than that, Ben has some good advice.
 
Jan 19, 2010
9,953
Hunter 26 Charleston
And smaller tires turn faster and put more wear on the bearings etc. as well as jarring more when you hit a pot hole.
 

walt

.
Jun 1, 2007
3,441
Macgregor 26S Hobie TI Ridgway Colorado
I have a lot of miles on a single axle trailer (but with a lighter boat – likely a bit under 3000 pounds) - just make sure the single axle system is rated for the load as mentioned already. Same as for your car.. it also doesn’t need to have four axles - just properly rated. When it comes time for maintenance or replacing tires, only half the work, half the cost. Less weight is also lower gas costs.

One thing about a single axle trailer however... the wheels on the ground form a pivot and weight to the rear reduces trailer tongue weight, weight forward increases tongue weight. The single axle trailer ends up being more sensitive to weight placement than the double axle trailer with its "distributed pivot" so you have to pay more attention to how the boat gets loaded. Too much weight to the rear can change the tongue weight enough that it degrades the towing stability even to the point of being dangerous. Not really a big deal - you just have to pay slightly more attention to the weight distribution (and usually only have to figure it out one time).
 
Jan 19, 2010
9,953
Hunter 26 Charleston
Hey BigJer40

One other thing to consider... I don't know the law in OR but here in VA a double axle trailer needs to have breaks and it needs to be inspected each year (hidden taxes). Single axle trailers do not need to be inspected and don't require breaks. So on the simple side of the equation a single axle trailer has a lot going for it. Oregon might have different laws but it might be something to add to the calculus.

r
 
Jul 1, 1998
3,053
Hunter Legend 35 Poulsbo/Semiahmoo WA
Tire Highway Speed Limit

Especially for smaller wheels, the tires can be rated for maximum speeds so this is something to check into.

This is a short question and answer post but it sheds the light on factors such as rated tire speed and load: http://en.allexperts.com/q/Tires-2359/2009/5/trailer-tire-speeds.htm

In this situation, the tire was placarded for 55 mph Max so something like this may throw a monkey wrench into the best of plans.
 
Mar 27, 2012
312
Seaward Fox Washougal WA
Thank you all so much. I put an offer in on this boat and trailer so we shall see. I am thinking I might change out axle and leaf springs if I get it. Is it as simple as that?
 
Apr 8, 2014
10
Clark San Juan 23 Moss Lake - Kings Mtn N.C.
I tow a San Juan 23 all over the place and is has a single axle trailer as delivered in 1977. I have kept the bearings well packed and they run cool. I am using 15" tires and run at or above highway speeds with no problems. I know the rating was for 3500 lbs and pulled the boat and trailer over a local scale to get a feel for my weight.
 
Aug 15, 2012
301
Precision 21 Newburyport MA
What is the weight of the boat you are looking at? Is it water ballasted or has a weighted keel? Some good points were made by some of the previous posters about making sure you have the right tire for the load. Currently I am towing a 2000lb boat on 10 inch tires. When I replaced them I made sure I got the ones with the correct ratings. My trailer was in tough shape when I got her so I had to replace the axles and springs as well. The 10 inch makes it easier to launch on shallow ramps. Like someone else mentioned smaller tires do spin faster than larger tires so you have to stay on top of maintenance. We tow the boat 300 miles round trip to a summer house every year. We take our time and the boat rides well on the trailer. The other trick with a trailer is to put the axle on top of the springs instead of below them, again to make it easier to launch.
 
Jun 8, 2004
8,867
-na -NA Anywhere USA
Some suggestions. Each tire will give you max carrying weight to include the weight of the trailer, boat, motor and gear. If you have a single axle, this will be times two for max capacity carrying weight. In addition, you do not want to load the trailer up to capacity either as there should be 10-20 % left for safety issues. Like the one response, many boats at 20 feet can differ some being a daysailor which is lighter or a regular cabin style sailboat which of course is heavier; thus, the specific boat information is most appropriate question to ask.