Posted 2008-02-11 10:36 AM (#76617) Subject: Trailer tire PSI?
Member
Posts: 24
Location: Dodge City
I have a 1998 S&H 3H Contender trailer. Currently it has car passenger tires on it as they seem to hold up pretty well, and wear pretty evenly on this trailer. That's what was on it when we bought it in 2003.My question is, what kind of PSI should these tires have? I had a tire fixed recently and the guy fixing it asked how much air I wanted in them. Not sure what to tell him. He went ahead and put 50 PSI, so when I used the trailer yesterday, I checked the air in the rest of the tires and they were about 40 PSI. Granted, the trailer hasnt moved since December, but I was just curious how much air trailer tires need?Thanks!
Posted 2008-02-11 11:15 AM (#76623 - in reply to #76617) Subject: RE: Trailer tire PSI?
Expert
Posts: 3802 Location: Rocky Mount N.C.
Are they the tires that came on the trailer when it was bought new? If so they are 10 years old!! 5 years is as long as I run a truck, trailer or car tire. Even if they are the same a you bought on it in 2003, the they are are already 5 or coming 5 years old. I would be looking for a new set of Light Truck or ST trailer tires. As Gard said, you can't go wrong with the maximum pressure stamped on the tire sidewall.
Posted 2008-02-11 3:42 PM (#76642 - in reply to #76623) Subject: RE: Trailer tire PSI?
Member
Posts: 24
Location: Dodge City
Originally written by retento on 2008-02-11 11:15 AM
Are they the tires that came on the trailer when it was bought new? If so they are 10 years old!! 5 years is as long as I run a truck, trailer or car tire. Even if they are the same a you bought on it in 2003, the they are are already 5 or coming 5 years old. I would be looking for a new set of Light Truck or ST trailer tires. As Gard said, you can't go wrong with the maximum pressure stamped on the tire sidewall.
Nope, they are not the original tires. I think we've probably been through a set of tires per calendar year since we've owned it. I rodeo, so there's a lot of miles on the trailer now! This was the first year that its really set in one place all winter!
Posted 2008-02-11 5:37 PM (#76650 - in reply to #76617) Subject: RE: Trailer tire PSI?
Veteran
Posts: 296 Location: Tennessee
Not sure how much your trailer weighs, but passenger car tires are usually not stout enough to safely use as trailer tires. They have thinner walls to allow the tires to flex as the car goes around corners. Flexing = heat. Theyre usually meant to be inflated to 28-35 psi. Trailer tires have stiffer sidewalls that don't flex and can handle more load without getting too hot. They usually are meant to be inflated to 65-80 psi or more. Look at the load rating on the tire and you'll see what I'm talking about.
Don't fill any tire above the tire's max psi rating.
Posted 2008-02-11 7:31 PM (#76661 - in reply to #76617) Subject: RE: Trailer tire PSI?
Expert
Posts: 1205 Location: Arkansas
All of our trailers at 3H capacity or better call for 80lbs cold pressure on the sidewalls, I believe I would upgrade the tires, for the eventuality of a blowout, the remaining tire can stand the sudden load up on it as you are stopping to put on the spare...What ply tread and sidewall are on the trailer now? Are these 16" tires?
Posted 2008-02-12 10:18 AM (#76698 - in reply to #76617) Subject: RE: Trailer tire PSI?
Elite Veteran
Posts: 736 Location: Western WA
I'm going to take a wild guess that passenger car tires (any tire with P as the first character in the size, like P235/75R16) are no way close to having the weight capacity as trailer tires (will have ST as the first two characters in the size, like ST235/75R16). As others have pointed out, your tires will have a max PSI and load rating stamped on the side. Most passenger car tires have a max PSI of 35. Trailer tires range from 80-110 PSI. A higher PSI generally means a higher weight carrying capacity, the sidewall strength has been discussed by previous posters. You need to calculate the capacity of your tires and compare to the weight of your loaded trailer. If you really do have passenger car tires on your trailer, I think you will find you are seriously overloading your tires.
Posted 2008-02-12 10:29 AM (#76699 - in reply to #76698) Subject: RE: Trailer tire PSI?
Expert
Posts: 5870 Location: western PA
Originally written by headhunter on 2008-02-12 11:18 AM
If you really do have passenger car tires on your trailer, I think you will find you are seriously overloading your tires.
This may also be the reason for the yearly tire changes. Most trailer tires go bad from old age before their thread is worn out. It would be less expensive to install one good set of tires, than have to replace four or five sets of the light duty tires.
Posted 2008-02-12 4:17 PM (#76732 - in reply to #76617) Subject: RE: Trailer tire PSI?
Member
Posts: 24
Location: Dodge City
Im not sure what the tires are for sure, but they are 15s. I will look tonight and see for sure. I havent had a blowout EVER with this trailer and tire combo, so something has got to be working. That or Ive just been really lucky!!
Posted 2008-02-12 5:40 PM (#76739 - in reply to #76617) Subject: RE: Trailer tire PSI?
Expert
Posts: 1416 Location: sc
A P235/75/15 tire is fairly common size found on trailers. Not my first choice in a trailer tire, but there are too many of them in use so I guess constant blowouts are not a problem.......also at 35 psi they do meet the weight ratings for a 3500# axle. If I were replacing those P tires, I would go with a ST225/75/15 in a load range C (50 psi), assuming 3500# axles. LR D for 5200# axles. Of course if its not broke, dont fix it.
Posted 2008-02-13 2:26 PM (#76791 - in reply to #76617) Subject: RE: Trailer tire PSI?
Expert
Posts: 1205 Location: Arkansas
Guess I worry about the what if factor. We do drive across the country in our own interests, as well has having been commerical haulers for 25 years, MOL.... I have had very few tire issues in the last 35 years, but on trailers of friends they have had blowouts, due to underinflation, overloading, aged tires, exceeding the speed rating on 100+ degree days, you name it........... I have had one, with a 10ply new tire, AAMOF, due to debris on the highway (head on collision, turn trailer over in the ditch or run over the debris...none good choices...a $190 tire gone!)... so blowouts are more of a concern as far as the remaining tires bearing a sudden weight increase, so it seems to me....good luck in whatever you get, it is hard to balance the economics of all this with the desire to take the best care of our rigs and cargo...
Trailer tire PSI?
