Trailer tires vs regular tires

As has been said : As a general rule P or passenger car tires are not a good substitute.
The load rating (in pounds ) posted on the sidewall of "P " tires must be derated by 9 % .
What sometimes happens is somebody has a " take off " tire from their pickup that has P rated tires and they mount them on their RV because their RV tires are "cracked " from the sun and ozone .
Then the P tires fail because they do not have adequate load reserve capacity , either .
As others have said an ST or LT tire with additional weight capacity in pounds is the cheapest way to prevent tire failure .
Presuming that you have load range "C" tires max 50 psi, now :
If you buy a load range D tire you can pick up 10- 20 % in load rating in the same size tire . If you inflate to 65 psi as shown on the sidewall you pick up reserve capacity .
Further , even if you miss an inflation check and your tires deflate from 65 psi to 50 psi you still have the same load rating as the C tire at 50 psi.

There are several classes of tires in discussion so far...here they
are and the rest of them

'ST' class, or trailer tires and not to be used on vehicles carrying passengers

Next higher class is 'P', or passenger car tires and when used on light duty
trucks (pickups and SUV's) must be derated a min of 9% from that tires sidewall
rating. Folks used to argue and even called me a lier when first came here over
12 years ago, but most tire sites (TireRack is the main source for folks here)
started to quote the RMA (rubber manufacturer Association) recommendations of
that (another thing folks don't seem to understand here is that when an OEM
'recommends' something and you didn't follow that recommendation...that OEM
most likely will deny warranty due you ignoring their recommendation)

Next higher class is 'LT', or light truck tires

Next higher class is 'Commercial', or semi truck tires

Next higher class is 'off road', or those +8 foot dia tires. Some weigh several
tons EACH

When changing class of tire from that vehicles (including trailers) OEM recommendation,
is to Re-Engineer that tire/suspension. Ditto when changing tire sizes from
the OEM recommended. Ditto changing wheel sizes/spec from what came from the OEM

Personally do NOT like ST class tires and my trailers all had converted to LT
class tires with wider wheels to make those LT tire sidewalls behave 'stiffer'

Careful on 'one load range higher', as if the discussion is with ply's, then
out of context without the tires size. Example is a LT245/75R16 load range E
(10 ply rating) might have lower capacity than a 285/75R16 load range D (6 ply
rating)

I can't understand why you would want passenger tires on a trailer. Just get a set of Maxxis tires along with a TPMS and enjoy life.

Its probably one tire size larger or equal. P tires need to have the sidewall load amount derated 10%. so as long as this is kept in mind, you should be fine. Many smaller trailers with 13 and 14" sized tires, usually single axle come with P metric tires. I have not had any issues as Barney noted from over flexing sidewalls etc. Then again, these tires do not have a lot of sidewall to flex causing sway and other issues.

Generally speaking tho, most will recommend that one an "ST" or "LT" style tire on a trailer. Like a lot of things in life, there are exceptions, the P tires are probably less than 10% of the time will they work in most situations.

Marty

For single axle trailers I don't think it matters much as long as you have the correct load range since the tires do not scrub sideways in turns. They may however allow too much sideways motion for a comfortable tow. Probably not though since most single axle trailers are lighter and smaller.

For dual axle trailers, the side walls of the passenger tires would probably be too flexible which may contribute to sway, and the chance of the tire coming off the rim during sharp turns would be possible as the tires drag/slide sideways. The sidewalls of the ST and LT tires are stiffer and resist this better.
Barney

Its not "an even" swap. There are many things to consider. As said, read up on it and make an informed decision.

You will need to do a lot more research before changing. This forum is a great resource for that. Do a search on "ST tires" and read on because there is a lot to learn still.

What do you mean by regular tires? If you have 16 inch rims, then yes LT tires are an acceptable alternative. 15 inch rims? Yes if you can find a 15 inch LT tire any more.