Trailer tire pressure

[makeall6]

I have a 2004 S/N on a Ramlin tandem trailer and just had a massive blowout on one of the front tires. Kapow! Even damaged the fender. New tire today and I noticed the guy at the tire store only inflated the tire to 20PSI. The label on the trailer says max of 35PSI. What is the best pressure to inflate? Thanks.

[Bruce_Butterfield]

The max pressure for any given tire should be listed on the sidewall of the tire. The tire is the critical point, not the trailer.

 

Its also important to keep in mind that tires "age out" well before they wear out - you obviously experienced what happens. Its wise to replace your tires every 4 years if you are trailering any distance.

[Rednucleus]

Two things: My buddies say trailer tires usually run closer to 50 lbs - were you sold a trailer tire or a car tire? 2nd - running low pressures create more heat than running proper pressures.

BTW how old are your other tires??

[jjackkrash]

The load and speed rating for a trailer tire are based on the max psi rating on the tire. I would always run right on max which should be measured cold.

 

Heat and age kill trailer tires. 4-5 years max.

 

Heat is generated by speed and asphalt/road temp. Check the speed rating for your tire. It is really a heat rating. If it is 105 out and you are going at, near or over max speed, that's a recipe for a hot tire and a blow out.

[ScottScott]

Not sure how many situations 20 would be correct. Even car tires have max psi higher than 35, tho 30-35 is often recomended by manufacturer. Trailer tires are usually max psi 60-80 (ours are 80.) With trailers inflate to max psi.

[skiboyny]

I think the pressure goes up with the sidewall ply. I would look for a 8 ply and keep them full. 35lbs has got to be a flimsy tire.

 

[jjackkrash]

PSI is driven by load range. That sounds like a Load Range B tire, which is about the flimsiest rating. Look for some Load Range C or better yet D tires with at least a 75MPH speed rating.

[makeall6]

Thanks to all. Great info as always. Cheers.

[Jmoski]

The trailer should have a placard on it with the exact tire spec listed.

 

Goodyear endurance trailer tires are great if they have them in your size - speed rated to 75mph, scuff guard built into the side wall in case you catch a curb, made in the US/Canada.

[Cnewbert]

... ditto all the above and be sure to look for the manufacture date on each tire. Take seriously the preceding advice on replacing any trailer tire at 4-5 years regardless of tread condition.

[Ski_Dad]

I run 50 in my 4 range C tires. 35 would not be right unless you have a pretty light boat.

[503Kento]

If it’s hot on you drive you should stop and check the pressure and make sure it’s not getting too high. You may need to take some air out during the high speed/temp portion of your drive. Obviously you would need to air them back up when things slow down/cool down,

[Jmoski]

@503Kento - it’s better to inflate trailer tires to the max psi when cold and just leave them. If your trailering long distance in extreme heat - taking pit stops along the way to let everything cool down is probably the better approach.

 

Inspecting your bearings is just as important, neglected hubs result in as many trailer breakdowns as old or under inflated tires.

[OREGON85]

If you had a blowout, you should probably buy 4 tires. Every trailer I have ever owned, when one went the rest were close behind.

[ScottScott]

Agree with @Jmoski. Pressure ratings are always given based on cold pressure (whether tire max rating or auto manufacturer specs,) they account for the heat increase on the road. In fact, a lower tire pressure will heat up more, which leads to many blowouts.

[jhughes]

The other day I was going down a major tristate tollway in IL and noticed a big bass boat on a tandem trailer- one of the wheels seemed cockeyed a bit. As I got closer the reason was obvious- one of the wheel hubs was riding directly on the axle spindle, metal on metal, zero bearing left whatsoever. So much so that the entire wheel was riding at an angle on the spindle, entire rim was dark from the heat, it was totally insane. The guy was probably going 80MPH, oblivious. I wonder how far he eventually made it. I had to pull off at an exit anyway before being able to warn him.

 

So, check your bearings too, at every stop. Full re-grease every couple years depending on amount of dips in the water.

[makeall6]

Thanks to all. I only tow a short distance to our lake. I have all of the tires at 40 psi. Things should be fine now.

[A_B]

My buddy had both tires blow out towing his fishing boat. Low miles but tires were 7 or 8 years old. Imagine cost of winching a boat and trailer up on a flatbed sans tires!

 

I have to imagine any SN trailer is probably running 225/75/R15 ST's and I have never seen a trailer tire in that size under 50 PSI. Maybe out there, just haven't seen them.

 

I am over due on my tires, but keep getting slammed with other stuff on Saturdays. I hope to get mine replaced this weekend!

[GaryJanzig]

I just replaced the original tires on a 1994 Correct Craft trailer which probably has less than 3000 miles on it. I has probably only been outside for 2 months its whole life. The tire dealer said the originals were still in good shape. Changed them as a precaution.

[BraceMaker]

Unfortunately most of our ski boat trailers are built on undersized axles which gives you somewhat stunted bearing/hub/tire options.

I personally am a fan of switching out the 3500K axles to 6k axles and then skip the whole low profile/aluminum wheel look and get real heavy duty trailer tires like 10 ply.

You lose the look but you get into the world of the tires that just don't blow out on you.

[jhughes]

While trailering my boat to storage this fall I stopped for gas about 5 miles in and checked the hubs for heat. One of them was burning hot, the entire rim was emanating heat profusely. Turns out one of the calipers was totally locked up on that side. I nervously limped the trailer home and swapped out the caliper. So, something else to keep an eye on and stay on top of. Had I not had to stop for gas, and jumped right on the tollway, this could have been a really bad situation.

[dbutcher]

I have a SN 200 sitting on a Ram-Lin single axle trailer. The tires are ST225 75R, load range E, 10 ply rating, maximum load capacity 2830 lbs. (each) at 80 PSI air pressure. The shipping weight of the boat trailer is 1,040 lbs., the dry weight of the boat is 2,800 lbs. Since there are two tires splitting the weight of the boat/trailer not even considering that maybe 100 lbs of the gross weight is transferred to the trailer hitch on my truck, my tires have more than enough capacity - even considering the weight of gas and gear in the boat. I do not, however, run them at 80 PSI. I run them at 65 lbs. because the ride for the boat is a little (perhaps a lot) smoother. I have used 65 lbs. pressure since the rig was new in 2015. I am on my second set of trailer tires due solely to age, but I have never had a blowout or flat. But, should I be running 80 lbs. tire pressure? I'm guessing that tire capacity diminishes as tire pressure is reduced. If so, how much or at what ratio? What do you all think?

[Zman]

@dbutcher You are good. For RV tires the manufacturers publish charts showing the ideal tire pressure for the actual weight on each axle. That pressure is usually somewhat below the max pressure noted on the tire sidewall.The ideal pressure is to be safely above those charted pressures, but not so much so to give you a hard, jarring ride. Most RVers go with about 5% above the charted pressures to allow for side to side variance on each axle.Since your trailer has a smart tire selection, tires with load ratings that well exceed what you have with your combined SN and trailer weight, 65 psi sounds about right.As you noted, going higher just makes a hard ride, adding little if anything for tire life.Unfortunately most boat trailers do not come with tires that have much, if any, "headroom" on the load rating, and have to be maintained at or very near the max pressure.

[dbutcher]

@Zman Thank you.

[ski6jones]

I read up on @dbutchers question a little because it was interesting. I found some charts that plotted carry capacity vs pressure for different tires. Looks like the rating for those tires is 2300# at 65 psi, formulas are in the link. They also contend that the ride should be softer at lower pressure provided the tires are inflated enough to carry the load, which yours are at 65 psi. The more you know.

[dbutcher]

@ski6jones Thank you too. I'm glad I asked.