Tent Trailer - Recommended Pressure > Tires' Max. Sidewall Pressure

Number_35

Number_35

Joined
Jul 7, 2014
Messages
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Location
Winnipeg MB CA
This is regarding my friend's tent trailer.

The label on the trailer calls for the tires (ST175/80D-13) to be inflated to 65 PSI cold.

I don't know what the 'D' means.

He recently had the tires replaced with radials. I believe they are P175/80R13, and the sidewalls state a maximum inflation pressure of 50 PSI.

Is it safe to inflate the new tires to the required 65 PSI?

Is it safe to run them at 50 PSI instead?

Would it be best to take them back and have them replaced with tires rated to 65 PSI?

Thanks!
 
What is the load rating on each?

No it not ok to inflate to 65psi.

Might be ok. would need to know trailer details.
and tire load ratings for both sets of tires.

Sounds like he got ford festiva tires instead of trailer tires.

Edit:
From generic info it looks like
Bias tire has a ply rating of 8 and a 1,610-lb maximum load at 65 psi.

A standard pmetric tire of that size is probably around load range 86 which is 1168 lb at 35psi
The load rating doesnt increase with additional tire pressure..

But we dont have exact information for the trailer or either tire.(old or new)
 
IMG_20240812_112537.webp
 
After your additional info looks like he got Radial trailer tires
They are inadequate for the trailer rating of 3000lb(this is likely a mistake of the tire installer too)
They should have notified him.

And since trailer tires are marginal I would get Load range D or upgrade to bigger tires(bigger tires = higher load) if they fit.
at a min you need tires rated for 1600+ lbs. Higher would be nice as the trailer might not always be loaded equally side to side.
 
The D should be the load range. But written the way you have it is odd. I see it is that way on the placard. Are they Radial Trail HDs? I see they are rated to 81 MPH. What does it actually say on the tire? Based on the weight they look like a load range C based off the 1200 and 1360 rating.

Each tire is good to 1200lbs at 50 PSI cold. Radial Trail HDs are pretty good. It is what I have been running on my 32 foot 7800 lbs for the past 8 years. 205/75R R 14 load range D.

Single axle trailer, you need a better load range tire. Carlisle makes a load range D in that size.
 
Last edited:
I'm pretty sure the D in your case means the original tires were bias ply. I wouldn't put p-metric tires on any trailer, although the Chinese trailer ties might not be that much better these days.
 
If they are past three years old-replace them. The issue with tent trailer tires is that that are small (13")-and spin like crazy at highway speeds.

I replace my Travel Trailer (5,000 pounds) tires every three years and have never had a single issue. I run Greenball tires exclusively-simply because they have never caused any issues.
And I run far more miles than the average weekend tower.
 
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CKN said:
If they are past three years old-replace them. The issue with tent trailer tires is that that are small (13")-and spin like crazy at highway speeds.

I replace my Travel Trailer (5,000 pounds) tires every three years and have never had a single issue. I run Greenball tires exclusively-simply because they have never caused any issues.
And I run far more miles than the average weekend tower.
Click to expand...
He did exactly that - replaced old tires with new. It looks like the tire shop did not understand the application, and installed car tires.
 
Number_35 said:
He did exactly that - replaced old tires with new. It looks like the tire shop did not understand the application, and installed car tires.
Click to expand...
They are not car tires. Those are load range C trailer tires. They put wrong load range on. Look up Radial Trail HDs. In fact here you go.
They are not they only company to make this type of tire. I have three trailers at the house all on Radial trailer tires. The 9000lbs float, the 7800lbs travel trailer and the 5500lbs boat.

Radial Trail HD

Bias VS Radial trailer tire.
 
Last edited:
c502cid said:
I'm pretty sure the D in your case means the original tires were bias ply. I wouldn't put p-metric tires on any trailer, although the Chinese trailer ties might not be that much better these days.
Click to expand...
Load Range D. 1570 per tire which means 3140 lbs on that axle which is more than the 3000 allowed, while not by much that is what the trailer manufactures do.
 
It probably has one 3000lb axle if you are lucky. A lot of time they account for tongue weight. So my trailer originally came with load range C tires and has 3500lbs axles even though the trailer can weigh a max of 7800 lbs. They are figuring about 10 to 15 percent of the load will be on the hitch. Discount had load range D tires that fit my wheels and my wheels were rated to 80 psi, so I can run them at the max of 65 psi. I change them out every 4 years. For the past 8 I have ran the Carlisle Radial Trail HD with no issue.

Just go get a set of the same size load range D tires and you will be fine.
 
Number_35 said:
He did exactly that - replaced old tires with new. It looks like the tire shop did not understand the application, and installed car tires.
Click to expand...

Respectfully-you are trying to help and apparently don't know what you are doing.....now that I read the above posts.

Do you even tow?
THOSE TIRES ARE TRAILER TIRES,BUT THEY APPEAR TO BE NOT TO HAVE THE PROPER WEIGHT CARRYING ABILITY THAT IS NEEDED.
 
Last edited:
ls1mike said:
Load Range D. 1570 per tire which means 3140 lbs on that axle which is more than the 3000 allowed, while not by much that is what the trailer manufactures do.
Click to expand...
Look at the the sidewall. The tires are not rated at 1,570.
R stands for radial construction. B means belted bias and D stands for diagonal bias construction. The last dimension listed in the size is the diameter of the wheel rim, which is most often measured in inches.

THEY APPEAR TO BE NOT TO HAVE THE PROPER WEIGHT CARRYING ABILITY THAT IS NEEDED.
 
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