Car Tires on a Trailer?

[ironhill]

I need tires on the trailer I pull my 14' tinner around on. Maximum weight might be 600lbs or so.

The rims are no great shakes so I thought I would replace them as well.

The exisitng set are BR 78-13's, 4 lug.

I can get pretty crappy/generic bias ply trailer tires w/ rims in a 478 -12 (an inch smaller) for around $80

Then I thought - Wallyworld has radial car tires for $27 for a 155 80 13 - the rims would be about $40 - about $67 for the set.

Is there any reason why I can't use the car tires?

Thanks!

 

[jacobcnc]

Re: Car Tires on a Trailer?

Car tires are not as stiff as trailer tires with that said i dont see a problem as long as you dont have tandems that is case the side walls flex to much. So they tend to heat up.

 

[ironhill]

Re: Car Tires on a Trailer?

Thanks - you are right that the characteristics of the tires are different but I wondered whether that was just as important for a light load such as mine or only the heftier boats.

and yes it is a single axle.

 

[kenmyfam]

Re: Car Tires on a Trailer?

Compare the rated load for the tires and the weight of your outfit including trailer and gear. Move on from there.

 

[slowleak]

Re: Car Tires on a Trailer?

On a rig that light the passenger car tires may actually be better in that they do have softer side walls. A trailer with an aluminum boat tends to bounce around a lot which isn't the best for the boat. The softer sidewalls may actually help absorb some of this shock.
I haul my 15' tinny on a bunk trailer with A78-13 tires, they are the same size tire that came on it when new 30 years ago. If I could find a smaller radial for it I'd probably go that way just to lower the boat a bit for easier launching. It also seems that passenger car tires last longer, I have a set of 165/80R13 tires on my one trailer that are 10 years old and no cracks, yet the new trailer tires I bought two years ago are already showing age cracks. Neither set have more than 50 miles on them. Maybe one of these days they'll make a tire that don't rot off the rims before they wear out.

 

[JimS123]

Re: Car Tires on a Trailer?

My trailer is a TeeNee 2800 pound model for a boat up to 19 feet long. The same frame size was used for a good dozen models. All they did was change the length of the tongue to match the boat length, and change the tires to meet the weight requirement.

In each length series, they offered 5 different weight ranges. In every case, the models with the lowest 2 weight ratings were equipped with auto tires. The middle model was an ST LRB, and the top 2 were ST LRC and D.

I realize that this was a few years ago, and a check of current trailer models from everybody shows ST tires, but if it was OK back then, I see no reason why its not OK to use car tires now, as lonmg as the weight capoacity is OK.

 

[wifisher]

Re: Car Tires on a Trailer?

As long as you don't overload them you can put any tire you want to on there. And you are not going to overload any tires with a 14' aluminum boat.

 

[marine4003]

Re: Car Tires on a Trailer?

The reason trailer tires are more money than car tires, is there build,trailer tires take more abuse,run faster then car tires (smaller size) heat up faster.Generally its not advisable to switch the 2, but with a light load you should be alright,on long runs check them every stop.

 

[Guest]

Re: Car Tires on a Trailer?

Yes what marine4003 said is true as long as you keep an eye on them such as checking pressure often, checking every stop to see if they are over heating as they do tend to run faster then the car does as they are smaller sizes, also if you tend to load ALL your gear into the boat instead of the tow vehicle will also add more weight to them. Just keep a good eye on them before, during and after every trip to keep you and the rest of us safer on the roads.

 

[H20Rat]

Re: Car Tires on a Trailer?

The reason trailer tires are more money than car tires, is there build,trailer tires take more abuse,run faster then car tires (smaller size) heat up faster.Generally its not advisable to switch the 2, but with a light load you should be alright,on long runs check them every stop.

?? If you are putting a car tire on a trailer, that means you have car and trailer tires that are the same size. So the argument about running different speeds doesn't work. (ever see the tire on a geo metro? (12 inch, 145SR12, speed rated to 112 mph) Those things are smaller than most trailer tires! And you can get actually get a geo up to highway speed, occassionally.)

Abuse? How? Car tires experience sidewall forces many many times larger than a trailer could ever exert. Your typical halfway decent car with good tires will hold close to 1 g of side force on a skidpad, the rear tires hold that load, the front tires are well above that because they are doing the change in velocity. Your typical boat would be on its side LONG before one G of force was exerted on the sidewall. And any bump your trailer hits, your vehicle probably has hit first!

 

[Home Cookin']

Re: Car Tires on a Trailer?

smokingcrater speaks wisely. Selling "trailer tire" for more is snake oil, especially for larger sized tires. Trailer tires cost more and fall apart just sitting there.

 

[dockwrecker]

Re: Car Tires on a Trailer?

??

Abuse? How? Car tires experience sidewall forces many many times larger than a trailer could ever exert. Your typical halfway decent car with good tires will hold close to 1 g of side force on a skidpad, the rear tires hold that load, the front tires are well above that because they are doing the change in velocity. Your typical boat would be on its side LONG before one G of force was exerted on the sidewall. And any bump your trailer hits, your vehicle probably has hit first!

That couldn't be any more wrong if you tried.
A 13" car tire is rated to maybe 900 lbs, maybe load range B
An st tire in the same size will be a load range C at least and D is available also.
You probably will never have a problem with your 500 lb tinny with car tires under it, but you sure as hell will if you try it with a 4000 lb boat. And good luck to you if your trailer ever gets inspected, you'll get a nice fine.
Trailer tires add stability and are constructed to handle heat differently than passenger tires when heavily loaded.
And I'm pretty sure a Geo Metro won't pull 1 g on a skidpad.

 

['78 Crusader]

Re: Car Tires on a Trailer?

That couldn't be any more wrong if you tried.
And I'm pretty sure a Geo Metro won't pull 1 g on a skidpad.

Though he mentions the Geo Metro in his post, I seriously doubt we'd classify a Geo as a halfway decent car....it's closer to the bottom of the pit. lol.

 

[bruceb58]

Re: Car Tires on a Trailer?

Abuse? How? Car tires experience sidewall forces many many times larger than a trailer could ever exert.

Except that a car has much softer suspensions typically. A trailer tire sidewall takes much more impact because of the stiffer suspension.

 

[wifisher]

Re: Car Tires on a Trailer?

That couldn't be any more wrong if you tried.
A 13" car tire is rated to maybe 900 lbs, maybe load range B
An st tire in the same size will be a load range C at least and D is available also.
You probably will never have a problem with your 500 lb tinny with car tires under it, but you sure as hell will if you try it with a 4000 lb boat. And good luck to you if your trailer ever gets inspected, you'll get a nice fine.
Trailer tires add stability and are constructed to handle heat differently than passenger tires when heavily loaded.
And I'm pretty sure a Geo Metro won't pull 1 g on a skidpad.

Well, if you have a 4000 lb. boat you will have bigger wheels to accommodate your BRAKES. A trailer with 13" wheels is a light duty trailer and will not overload any tires.
As far as inspections go, there is absolutely no law that requires a certain type of tire on a trailer. Load rating must be at or above actual load, and there must be 2/32" of tread. These are the ONLY requirements.

No tire will add stability to a vehicle. If it is overload or underinflated it can reduce stability slightly. Stability is mostly influenced by vehicle construction and shocks.
Heat requirements for trailer tires and passenger car tires are exactly the same. If anything there may be trailer tires that will withstand less heat as they are intended for off-road use.

 

[wifisher]

Re: Car Tires on a Trailer?

Except that a car has much softer suspensions typically. A trailer tire sidewall takes much more impact because of the stiffer suspension.

Ummm... No. The tire is unsprung. It hits the road at whatever speed you are driving. Suspension can only affect the sprung portions of the vehicle. Also any effect of the suspension is not realized in the tire until after it is past the obstacle, and the tire has absorbed as much impact as it is going to.

 

[bruceb58]

Re: Car Tires on a Trailer?

Ummm... No. The tire is unsprung. It hits the road at whatever speed you are driving. Suspension can only affect the sprung portions of the vehicle. Also any effect of the suspension is not realized in the tire until after it is past the obstacle, and the tire has absorbed as much impact as it is going to.

Disagree. You feel that the impulse is absorbed entirely by the tire which it isn't. Think about it..if the spring on a car requires 1000 lbs of force to move it an inch and the spring on a trailer requires 2000 lbs to move it an inch, the car tire will have less force to have to absorb before the spring moves. While the tire is absorbing the energy of the bump, it is transferring force to the spring. It's not a step function. I agree there is some damping action provided by the tire.

I need to dig up my mechanical engineering notes now!

Trailer tires do add stability(less sway) because of their stronger sidewalls.

 

[sschefer]

Re: Car Tires on a Trailer?

O.K. why am I not seeing the law being referred to here? It is illegal to run non-trailer rated tires on a trailer. Granted, only a over-zelous cop would look at them and write you up but if you were in an accident while towing, you can rest assured that someone will bring the tires into the picture.

Everybody wants a boat but few of us consider all the costs that go along with making boating a safe and fun activity.

 

[bruceb58]

Re: Car Tires on a Trailer?

It is illegal to run non-trailer rated tires on a trailer.

I don't think that is true.

I would be very interested in seeing where that law is. That being said there are lot of things that aren't against the law but may affect your safety. There is no law against stepping on a banana peel but I wouldn't do it. I run ST tires becuase I feel they are the best tires for the application.

 

[wifisher]

Re: Car Tires on a Trailer?

Disagree. You feel that the impulse is absorbed entirely by the tire which it isn't. Think about it..if the spring on a car requires 1000 lbs of force to move it an inch and the spring on a trailer requires 2000 lbs to move it an inch, the car tire will have less force to have to absorb before the spring moves. While the tire is absorbing the energy of the bump, it is transferring force to the spring. It's not a step function. I agree there is some damping action provided by the tire.

I need to dig up my mechanical engineering notes now!

Trailer tires do add stability(less sway) because of their stronger sidewalls.

The spring rate is the important figure here. The face of the tire will absorb 100% of the initial impact, and a lesser amount over time depending on the rate that the sidewalls, rim, shackles, spring, etc. takes the load. (yes, there is deflection in all of these components. However miniscule.) The time it takes to move a spring 1 inch is much longer than the time it takes to cross a bump in the road at 60 mph. This is why you feel the bump in the road. If the spring could react as fast as it meets resistance, you would not feel the bumps.

My point about stability is that a tire will not add to stability, it will only subtract from it. If an improper tire is put on, it will have "soft" sidewalls. However, on a small boat trailer, the tire will not make enough difference to notice.