Advice needed re tire capacity. I'm at max load

[Moody Blue]

Finally have the boat/trailer mobile for the first time since I've owned it. Took it over to the local scales and had the package weighed.

Van, myself, boat, motor and trailer weighed in at 5886 Ib. Curb weight of the van is 3941 Ib and I'm 190 Ib, so the boat, motor and trailer weighs 1754 Ib.

Trailer has a 2000 Ib axle with 5.70 x 8" load range C tires with a max combined rated load of 1820 Ib (910 ea). Basically I'm loading the tires (and axle) almost to maximum capacity right now.

1) Should I be looking at upgrading the tires to 5.3 x 12 load range C tires. They are rated at 1050 Ib ea. I have the fender clearance to do so.

2) What about the axle capacity, am I OK to run within 250 Ib of max capacity?

 

[JB]

Re: Advice needed re tire capacity. I'm at max load

Eeek!!

You do not need new tires or a new axle. You need a new trailer with at least 3,000# capacity and brakes (bet the current trailer has no brakes).

Good luck.

 

[Silvertip]

Re: Advice needed re tire capacity. I'm at max load

What JB says. You also need to allow for fuel at about 6 pounds per gallon. Coolers, fishing tackle, battery, and other stuff.

 

[nlain]

Re: Advice needed re tire capacity. I'm at max load

I am inclined to agree with the two guys above, but also just to be sure, if you can, go back to the scale, talk to the guys running the scale to see if the will let you ease the the van on the scale, keep the trailer jack off the scale, unhook the trailer and jack it up off the hitch, get them to record weight, reconnect trailer pull on scale and take weight again then deduct the van from the total, do the math on fuel, batteries, coolers and other stuff then see where you are. As I said in the beginning I am inclined to agree with both the guys above.

 

[Moody Blue]

Re: Advice needed re tire capacity. I'm at max load

Oh no, worse than I thought. What is the reason for a heavier trailer with brakes? Not a dumb question I hope . I can legally tow 3000 Ib without brakes here in Ontario. My van is factory equipped to pull 3500 Ib.

The weights noted in my first post did include battery and fuel, but that's not too big of a deal weight wise.

As for the axle capacity, am I really pushing the safe limits of its capacity? Its rated at 2000 Ib, should I not be able to load it to 2000 Ib safely? Not questioning the advice, just want to understand clearly before spending more money than necessary.

I can easily put a 3500 Ib axle and beefier tires on and be good to go if I had to, yes?

 

[dingbat]

Re: Advice needed re tire capacity. I'm at max load

You say the boat, motor and trailer weigh 1754#. How much does the trailer weigh?

Both of the trailer manufactures I've worked with don't count the weight of the trailer when rating trailers capacities. I would check to see how your trailer is rated before you panick.

 

[Moody Blue]

Re: Advice needed re tire capacity. I'm at max load

Guessing the trailer weighs around 300 Ib's but could be way off. Its a 40 yr old model without any identifying makes or models so no idea how it would have been rated. It does have 1" spindles rated at 1000 Ib each, of that I'm sure.

 

[redone4x4]

Re: Advice needed re tire capacity. I'm at max load

heres a pic of my trailer....it weighs about 550 lbs according to specs:

EDIT: Please downsize the pic so that it does not require scanning to read the thread.

 

[Randybeall]

Re: Advice needed re tire capacity. I'm at max load

Trailer capicity is determined by axle capicity. You could tow a 2000 lb gross weight, however the first time you hit a pot hole or serious dip in the pavement you will begin to bend the axle with the impact of the sudden change of direction. You should have about 20% over capacity or more in trailer load rating.

 

[dingbat]

Re: Advice needed re tire capacity. I'm at max load

You should have about 20% over capacity or more in trailer load rating.

Where did you come up with this 20% number? How does this relate to the axles design load and service factor ?

 

[Titanium48]

Re: Advice needed re tire capacity. I'm at max load

What's with all the doom and gloom?

First of all, the curb weight of a vehicle is like the published dry weight of a boat. It doesn't include things like fuel or extra-weight options, it's the weight of the base model as it rolls off the assembly line. Subtracting the driver and tow vehicle curb weight from the combined weight is probably overestimating the trailer weight a bit.

Second, even if we take the 1754 lb at face value and add 200 lbs of fuel and gear, the trailer is still under 1/2 of the curb weight of the tow vehicle. Remember that the boat has actually been weighed, and I would guess that things like batteries, covers and safety gear were still in or on the boat at the time, so 200 lb is probably pretty generous. While trailer brakes are never a bad idea, they aren't essential here.

Third, let's assume that the total, ready to go package is 2000 lbs. 10% of that should be tongue weight, so a 2000 lb axle will still be 10% under its rated load. Being well under the axle load rating is never a bad idea, but the axle manufacturer should have already accounted for transient overloads like hitting potholes when setting the rating, so unless you are constantly driving on rough gravel roads you shouldn't need any additional margin.

Finally, back to the original question. Yes, it would be a good idea to get the 12 inch LRC tires for the weight rating, but they will raise your trailer by 1.5 inches. Another option would be to try to find 5.7-8 tires in LRD. Same load rating as the 5.3-12 LRC, same height as stock.

 

[Moody Blue]

Re: Advice needed re tire capacity. I'm at max load

OK, given this some more thought.

Titanium48 makes a good point in that I didn't take into account the tongue weight. I measured the tongue weight at 155 Ib or about 9% of the total weight which is just about dead on where it should be . So that means the tires and axle are only loaded to about 1600 Ib. These weights include full tank of gas, battery, anchor, safety gear etc.

I'm pretty comfortable with just replacing the tires/rims with the 530 x 12 LRC. The axle is loaded to about 80% of its rated capacity so I have some overhead there.

As for brakes, the law says I don't need them and most boat trailers of this size and even the smaller pop-up type camper trailers don't come with brakes. I maintain my tow vehicle regularly and it came equipped from the factory to tow 2000 Ib without brakes and 3500 Ib with brakes.

 

[Silvertip]

Re: Advice needed re tire capacity. I'm at max load

There are two load ratings for trailers: 1) Load capacity = the load the trailer is rated to carry and this is the issue as it not always clearly specified in the literature. 2) GVWR = Gross Vehicle Weight Rating. This is the total of trailer and everything on it and in the boat. You therefore should not have 2200# for example on a trailer with a GVWR of 2000#. The next issue is the rating on the sidewall of the tire. To comply with the GVWR rating, the tire capacity must equal or exceed the GVWR. Same for the springs.

 

[Moody Blue]

Re: Advice needed re tire capacity. I'm at max load

Unfortunatley the trailer is so old that there is no identification or load ratings on it. I do have the original ownership from 1971 and have tried contacting the mfr but they have long since gone out of business.

Axle spindles and bearings are 1" which indicates 1000 Ib rating each. New tires will be rated at 1045 Ib each so I think I'm in the clear as long as I don't load up the boat too much.

Leaf springs are pretty heavy, infact maybe too heavy. They are 5 leaf. Have done some searching and can't find any reference to load capacity and spring construction (3, 4, 5 leaf).

 

[canoeist]

Re: Advice needed re tire capacity. I'm at max load

Put the biggest tires & rims on it you can. It will tow better, be easier on the bearings and burn a lot less fuel while towing.

 

[Jeep Man]

Re: Advice needed re tire capacity. I'm at max load

I don't think you have a lot to worry about Moody. Trailers in Ontario are required to have brakes when in excess of 3000 lbs. The tires you have meet minimium requirements, which to me says "Go bigger". Titanium made some good points, but if your going to spend some money, your 12" wheel is better for the bearings if the additional height isn't going to affect launching and center of gravity. You are at approximately 75% of your load capacity. If you are travelling at highway speeds and/or long distances, upgrading the axle should be in your thoughts.
And finally, you only have to tow it an hour north to Muskoka for the BEST boating. LOL

 

[Moody Blue]

Re: Advice needed re tire capacity. I'm at max load

Posting back with an update.

Took just the van and had it weighed and came out heavier than the published specs by about 220 Ib. So, that means the boat and trailer weighs 220 Ib less than I thought originally.

Even though I'm only loading the existing 570 x 8 tires to 80 %, I'm still going to go ahead and upgrade to the 530 x 12 tires and rims to give me more load margin.

Thanks for everyone's input and advice.