Passenger car tires on trailer?

Erock

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Jun 22, 2009
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I have a 19ft 4 Winns that I tow on a roller trailer. It has passenger car tires on it. They don't seem to bulge too bad, but some people have told me that it is very unsafe. On the other hand , some people have told me they have towed with passenger tires for years and never had a problem. I just wanted to get a few more opions. Thanks.
 

Bifflefan

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Re: Passenger car tires on trailer?

To tel the truth, a pass. car tire is fine to tow with as long as you dont go over the weight rating. The only difference in a trailer tire to any other tire is the trailer tire is not made for "everyday" driving. And it (depending on the load range) has a little more cords in the side wall. If you have a tandem axle trailer it will pull better down the highway with pass, car tires but it will take a little more effort to do tight turns as they grip better.

Just air them to the manufactures recemended PSI and dont exced the weight rating, and they will be fine as frog hair.

See my avitar, Semi Truck tires and wheels.
 
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Mark42

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Re: Passenger car tires on trailer?

That makes for some interesting reading. But for now I'll stick with traditional trailer tires because I have not experienced any problems using trailer tires.
 

mphy98

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Re: Passenger car tires on trailer?

This comes up here all the time. My 2 cents is that they make car tires for cars, truck tires for trucks, trailer tires for trailers. Some engineer with way more degrees than I figured out there is a difference, so I paid more for the trailer tires and put them on the old boat. Safety does sometimes come at a price.
 

45Auto

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Re: Passenger car tires on trailer?

Not necessarily an engineer that figured out that there is a difference. In many cases it's a marketing guy who figured out that people would pay more for a certain item if they named or targeted it towards a particular market segment. You are possibly paying more for a tire that is less safe than the cheaper alternative. I'm an engineer for a major corporation, and you can't imagine the stuff I've seen pulled by our Business Development (marketing) guys. The product might be the exact same or even inferior to the same product in other markets, but the "perceived value" lets them sell it for more. Might be worth doing some research and looking at the specs on car, truck, and trailer tires before you blindly purchase them based on what the manufacturer wants you to buy ........

You realize that there is no requirement or law that you use ST (Special Trailer) tires on a trailer? This is a designation created by the tire industry. Guess what they're trying to sell? My gut feeling is that with the nanny government and litigious society we've had for the last 20 or 30 years, if there was a documentable safety difference you would be required by law to use "ST" tires on a trailer.

I've never had to put tires on a trailer. All my trailers have always come with ST tires and I've never had to touch them. Longest I've owned one though is 7 years. But if I do need to, I'll definitely be doing a little research before paying extra for some "Special Trailer" designation.

This is a pretty good basic article on trailer tires:

http://www.automedia.com/Tow_Far_-_Trailer_Tires/ccr20040501tt/1
 

ScottinAZ

Senior Chief Petty Officer
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Jun 25, 2009
Messages
767
Re: Passenger car tires on trailer?

observe the max load rating for the tires, and you should have no issues. The tire itself does not care that it is on a trailer, and the "free rolling" thing is pure BS. the non drive tires on your car are also "free rolling"
 

JB

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Re: Passenger car tires on trailer?

Had very bad experience using car tires on a boat trailer. 3 blowouts on one, 3,000 mile trip.

After I put ST tires on the trailer (same size) I had no further trouble for 15,000-20,000 miles.

I, too, have seen marketing types mislead the market, but not with federally regulated products like tires. I am also not quite as cynical as our friend, .45Auto.

Use trailer tires on trailers and car tires on cars.
 

lowkee

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Re: Passenger car tires on trailer?

Hmm, guess I'll be looking at the weight rating of some car tires before getting ST tires.

I have had 5 flats in 6 months with 4 brand new car tires (on my car). A flat doesn't mean the tire is rated wrong. It could be a bad batch or just a cheap tire. Seeing as we are all boaters, I think it goes without saying, many marine items have absolutely nothing special about them except the word 'marine' in place of 'auto' (and maybe a white paint job).

Why some think this wouldn't follow to products such as tires I don't understand. Gas is federally regulated, too. Who here fills their boat with Mobil Premium gas and no other, even though Mobil gas come from the same pipeline as all other gas, and most marine engines aren't even made for premium gas (the tiny difference there is between it and regular)? I would guess near noone, as it is just advertising.

Calling someone cynical because they choose to do their due diligence and have direct experience with 'empty marketing' is dismissive and perpetuates ignorance. I'd love to learn the difference (if any) between how a ST tire is manufactured or if they just get a different sidewall label and what the cutoff (and more importantly, overlap) is between a passenger tire and a trailer tire.

I think one factor may be the rubber hardness, as bifflefan mentioned, passenger tires may be designed to grip better and, as such, may be softer rubber. After all, a trailer just has to follow, not grip. Assuming this is true, the high mileage passenger tires would be best, as they are harder rubber (performance tires are much softer, hense the low mileage warranties on them).

Beyond all of that, I'm all for discouraging empty marketing by purchasing the cheapest equivalent product in hopes the 'marketing' lines are dropped as a failed price hike idea. Sort of like a the lower shift cable tool, which is just a really deep 9/16" socket.. $30 for that? No thanks.
 

lowkee

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Re: Passenger car tires on trailer?

In doing some research on this subject, I found a good posting about it where someone actually wrote goodyear.

Goodyear/ Dunlop's written response to me today, 15 August 02, was:

Thank you for contacting our website. To address your concerns; a special trailer tire is not a must, the factor to consider is the load carrying capacity. If the Trailer does not overload the tire(s) then they are acceptable.

In the original letter the guy asked about the difference between LT (light truck) and ST, not passenger vs ST. From what I've read so far, passenger tires are designed with more flexible sidewalls (softer ride and better grip), which is actually a cause of trailer sway. Given the limited research, I will likely steer clear of passenger tires, but consider light truck tires as a viable alternative to ST tires, so long as your remain within weight specs.
 

Mark42

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Re: Passenger car tires on trailer?

A lot of boaters have trailers with 8 and 12 inch rims. Auto tires are nearly non existant in those rim sizes, and even if you do find a 12" auto tire, it will not have the 1045 lbs load capacity of a 5.30x12 trailer tire.
 

Bifflefan

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Re: Passenger car tires on trailer?

Just to add a little more fuel to the fire here, I too have 12" tires on the trailer. I needed new ones so I went to the local tire shop and found trailer tires for 49.99 each (tire only). Then i went to Harbor freight and found exactly (note the exactly) the same tire with a new spoke wheel for 50.00.

Pays to shop around a little.
 

lowkee

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Re: Passenger car tires on trailer?

A lot of boaters have trailers with 8 and 12 inch rims. Auto tires are nearly non existant in those rim sizes, and even if you do find a 12" auto tire, it will not have the 1045 lbs load capacity of a 5.30x12 trailer tire.

That reminds me. If you have a 3000lb boat and a single axle trailer. Do the tires need to be 1500lb (min) tires or 3000lb tires? I would figure going around a corner puts at least 70% of the weight on a single tire.

How does the weight rating work into the equation for that scenario?
 

dingbat

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Re: Passenger car tires on trailer?

Here is a copy of the Goodyear tire inflation load charts. Check out page 10. They give you load figures for using passenger car tires on a trailer.
http://hmcclub.homestead.com/Goodyear_Tire_Inflation___Load_Charts.pdf

As far as sway is concerned, I've used passenger cars tires on a tandem axle before and found them no more condusive to sway than the ST rated tires I'm currently running.
 

Erock

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Jun 22, 2009
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Re: Passenger car tires on trailer?

Thanks to everyone for all of your input.
 

109jb

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Re: Passenger car tires on trailer?

That reminds me. If you have a 3000lb boat and a single axle trailer. Do the tires need to be 1500lb (min) tires or 3000lb tires? I would figure going around a corner puts at least 70% of the weight on a single tire.

How does the weight rating work into the equation for that scenario?

Weight ratings on tires are PER tire. A pair of 1500 lb rated tires would be good for a 3000 lb load on a single axle trailer. 4-1500 lb tires on a tandem trailer would be good for 6000 pound total load.
 

Mark42

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Re: Passenger car tires on trailer?

That reminds me. If you have a 3000lb boat and a single axle trailer. Do the tires need to be 1500lb (min) tires or 3000lb tires? I would figure going around a corner puts at least 70% of the weight on a single tire.

How does the weight rating work into the equation for that scenario?

The combined load range of the tires must support the weight of the boat & trailer. For example, my Bayliner boat & motor weigh 1100 lbs. The trailer weighs (I guessing) 300 lbs. The tires are 5:30x12 load range "C" (1045 lbs each) for a total load capacity of 2090lbs. So each tire although not enough to carry the entire weight of the boat, is close. It takes BOTH tires to support the total weight of the boat, trailer and gear.

The extra capacity is taken up by a few bicycles, full fuel tank and beach toys stuffed in the boat! :D
 

skargo

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Re: Passenger car tires on trailer?

I have multiple trailers and will always use trailer tires for my trailer. I got brand new rims and tires for my boat trailer for $75 shipped to my door(205/75D14) so cost is not a contributing factor in my decision.

Now, if you have an accident because of a tire failure, and hurt someone, do you want to take the chance that some insurance companies lawyer is going to say you had improper equipment on your trailer? Not I!
 

Mark42

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Re: Passenger car tires on trailer?

I wish my trailer had shocks. I think it would reduce the impact load that the boat gets, and reduce the bounce and hop from hitting big pot holes and the like. I think shocks make a trailer steady.
 

Fl_Richard

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Re: Passenger car tires on trailer?

My spare is a passenger car tire. The other four are trailer tires. Passenger tires on a tandem setup is a recipe for disaster.
 
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