Tandem Trailer Capacity Questions?

[Gearhead62]

I am not the original owner, but I have an '87 Celebrity (defunct) 21 Bowrider w/ 350 cid Merc....It rides on a Shoreline (defunct) Tandem Trailer: 5-Lug, 13" wheels, tires are rated for 1300 lbs max - all are kept at max listed psi

At full psi, (radial) tires bulge a bit at surface contact (normal for radials), but on slow tight turns, appears that tires are under much strain, appear to lean on one of the axles

Have plenty of clearance under fenders to go from 13" to 14" tires and that would allow me to upgrade load capacity, if needed

Seeking answers / advice on following Questions:

Any idea what boat weight might be?
Any idea what existing trailer capacity might be?
Are 13's common for tandems?
Upgrade to 14s?
No big deal?

Thanks in advance for any insight / suggestions, or shoot me questions seeking more info.

 

[NYBo]

Re: Tandem Trailer Capacity Questions?

According to this page, the dry weight of your boat is about 2900#. Therefore, even adding 1000# of "stuff" (fuel, etc.), your tires should be fine.

BTW, upgrading just the tires doesn't increase the safe load capacity of the entire trailer.

 

[Silvertip]

Re: Tandem Trailer Capacity Questions?

As for the leaning/strain on one of the axles when turning, think about it! These wheels do not steer. Try dragging your car around a corner with the steering wheel locked. Same effect on a tandem trailer. The reason it works on a trailer is the wheels are closer together.

 

[Gearhead62]

Re: Tandem Trailer Capacity Questions?

Thanks for the reference info on dry weight....

If I go to 14" tires, my goal was to raise the per tire capacity from 1300 lbs to 1700 lbs, thus picking up extra 1600 lbs (400x4). I can't find any 13" tires that increase the load rating and these 13s show stress on tight corners

 

[BaileysBoat]

Re: Tandem Trailer Capacity Questions?

Agree with NYBo. Just make sure you have fresh tires.

You probably have a trailer rated to carry 4000 lbs.



http://www.shorelandr.com/pages/t_specs.aspx?type=boat&productID=276

 

[Bondo]

Re: Tandem Trailer Capacity Questions?

If I go to 14" tires, my goal was to raise the per tire capacity from 1300 lbs to 1700 lbs, thus picking up extra 1600 lbs (400x4). I can't find any 13" tires that increase the load rating and these 13s show stress on tight corners

Ayuh,... If you have 1 ton axles, you've already got More tire capcity than you have axle capacity...

Either way,... The bigger tires will Still scuff when turning sharply....

 

[Gearhead62]

Re: Tandem Trailer Capacity Questions?

All - Thanks for info

These tires need to be replaced next season, so I might just jump into 14s.

And yes, I get the physics on why they strain, but these 13s really bend on corners.....I have seen bobcats / const eqpt on tandems and no strain cornering....I probably just have aging tires with sidewalls losing firmness

Thanks again

 

[TruckDrivingFool]

Re: Tandem Trailer Capacity Questions?

I always heard it called scrubbing, any tandem setup will do it. Going to 14" tires may make it worse as you could end up with taller sidewalls giving you more flex. Just food for thought.

 

[NYBo]

Re: Tandem Trailer Capacity Questions?

Get the highest load-rated tires in your current size and pump them up to the maximum pressure, which is listed on the sidewall. The higher the load rating, the higher the maximum pressure (tire size being the same). This should minimize sidewall flexing.

 

[Silvertip]

Re: Tandem Trailer Capacity Questions?

There are four aspects that enter into trailer capacity and tires are only one of them. Spring rates, spindles/axle capacity and frame are others. It does no good to install tires with a higher load capacity than the springs, axles, or frame can tolerate. Install bigger tires if you wish, but don't think just because you added capacity you can USE it.

 

[Gearhead62]

Re: Tandem Trailer Capacity Questions?

10-4 on that Supreme....

I'm at a disadvantage as I cannot find specs on this Shoreline Trailer (no labels, markings, nothing online - out of business), so I'm cross referencing other mfr's models that have similar published specs, frame specs, axle specs, leaf counts, etc., just to get an idea what this trailer was designed to handle and if it was shipped w/ 13s..?

I've run fine with these 13s for a few years, and just got a bit worried when I recently saw these really straining on corners. They are at max psi, but the back pair looked like they were ready to jump off the rim while backing up on a soft turning radius! maybe its normal as some are suggesting?

New tires is the direction and I'm not increasing the load - just thought these current 13s might have been slapped on by a novice and that 14s might be a better match for load.

 

[Bondo]

Re: Tandem Trailer Capacity Questions?

I'm at a disadvantage as I cannot find specs on this Shoreline Trailer (no labels, markings, nothing online - out of business),

Ayuh,... The axle spindle diameter will tell you the axle rating...

 

[Silvertip]

Re: Tandem Trailer Capacity Questions?

If the inner and outer wheel bearings are the same size the axles are likely rated for roughly 2000# each. If the inner bearing is 1-3/8 diameter and the outer is 1-1/16 the axles are likely 3500# each. Axles and springs are usually matched to provide for maximum axle capacity. From the manufacturer however, tires will vary depending on the load capacities listed on the label. Although the springs and axles may be the same for all loads, tires, like on cars and trucks have several options which affects the maximum load. there may even be a tag spot welded to the axle indicating it's manufacturer and the capacity. Axles, spindles, wheels, tires, hubs, and brakes are rarely made by the trailer manufacturer -- they are outsources.

 

[Gearhead62]

Re: Tandem Trailer Capacity Questions?

Very helpful, excellent additional info.....