Sizing Tires

Ok, I'm a little confused......

When sizing the tires for your trailer you add up the weight of the trailer and the boat/equipment.

On mine the trailer is 1200lbs and the boat is 1600lbs for a total of 2800 lbs. Do I:

a: get tires rated for a minimum of 2800 lbs
b: since the load is divided across two tires do I get tires with a minimum rating of 1400lbs

Re: Sizing Tires

Tires are rated for the load each can carry, so answer "b" is correct, sorta. Add some extra capacity to account for the extra stuff that inevitably ends up in the boat. In your example, tires rated for 1700# or so should give you enough wiggle room.

Re: Sizing Tires

Why are you confused? The weight capacity is specified on the tire. Obviously one tire can support the weight specified on the sidewall at the maximum stated inflation pressure. Trailers can have two, four, six, eight, or even more tires. So the total weight capacity is the sidewall capacity x the number of tires. I also question the validity of your stated trailer weight. Why do you have a trailer that weights nearly as much as the boat.. Or do you have a trailer that says GVWR 1200 which means it's capacity is 1200 pounds, which is NOT what it weighs. It does mean the trailer is overloaded with a 1600# boat if that's the case. You really nead to figure out what you really have. And just so you know, if your boat is an outboard, the manufacturers published boat weight is minus engine, fuel, gear and any other stuff you carry in it. The manufacturer has no idea what engine gets installed and all engines do not weigh the same so you have some homework to do.

Re: Sizing Tires

Some manufacturers include the weight of the standard outboard in their specifications if they sell a complete package deal. I know Bayliner does that. But after I responded, I also thought his trailer weight sounded very high. Good catch.

Re: Sizing Tires

When in doubt, find a public scale, most truck stops have them, weigh your boat with trailer and all the gear you normally carry including gas. The weight on your tires is the weight they will have to carry. This eliminates guessing.

Re: Sizing Tires

Silvertip said:

Why are you confused? The weight capacity is specified on the tire. Obviously one tire can support the weight specified on the sidewall at the maximum stated inflation pressure. Trailers can have two, four, six, eight, or even more tires. So the total weight capacity is the sidewall capacity x the number of tires. I also question the validity of your stated trailer weight. Why do you have a trailer that weights nearly as much as the boat.. Or do you have a trailer that says GVWR 1200 which means it's capacity is 1200 pounds, which is NOT what it weighs. It does mean the trailer is overloaded with a 1600# boat if that's the case. You really nead to figure out what you really have. And just so you know, if your boat is an outboard, the manufacturers published boat weight is minus engine, fuel, gear and any other stuff you carry in it. The manufacturer has no idea what engine gets installed and all engines do not weigh the same so you have some homework to do.

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I was speaking in general about the weights. No that is not the weights of the equipment I have. My question was only asked to ensure my understanding of how the tires are rated so I do not make a mistake in replacing the mis-matched tires that are on this used trailer. Being an engineer one thing you understand that each industry has its own nomenclature and rating systems that do not necessarily translate to other applications.

Re: Sizing Tires

nuffsaid said:

When in doubt, find a public scale, most truck stops have them, weigh your boat with trailer and all the gear you normally carry including gas. The weight on your tires is the weight they will have to carry. This eliminates guessing.

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I have all that covered. As I said before I know the weights of my equipment I was just throwing generalized numbers out as an example.

Re: Sizing Tires

Sorry for the confusion with the weights everyone. But thanks for the responses.

Re: Sizing Tires

Various rating systems by various manufacturers is true only to a point. Tires use a standard rating system and have for years. Load capacity is load capacity expressed in pounds at a specific tire pressure. It is all printed on the sidewall of the tire. Trailers also have GVWR and GAWR (gross weight and gross axle weight) ratings on a tag somewhere on the trailer. In fact there may be several groups of ratings which depends on the tires installed even though nothing else changes on the trailer itself. When people post numbers we most of us know whether they are "reasonable" which is why I questioned them. If youj are going to be arbitrary, then by all means say so. Nobody likes to have to second guess things.