Trailer Tire Pressure for My Tin Boat

[MarPar]

Gents!

I know trailer tire pressure is of utmost importance, but I would like to see where the ends of the safe spectrum are. I purchased these wheels and tires new a couple of years ago...

https://www.etrailer.com/Trailer-Tires-and-Wheels/Kenda/AM31985.html

I have used them a few times and found out that my boat and trailer are a bit too light for them as when they hit bumps and potholes etc at the max 70psi, the trailer hits HARD. Rattles everything and the trailer even hops a little to the side.

The last time I took the boat out I went to my buddy's lake 30 miles one way and lowered the PSI down to 55. Rode MUCH better and soaked up the bumps very well. I'm pretty sure 55 is too low and I risk a blowout, so I started poking around the interwebs for background.

Etrailer experts says 65PSI is recommended for this tire with a D load range...

https://www.etrailer.com/question-2...znLJfsEdBWYtFW7_tc_DQwfJx8adGFXxIKniGVfg0ZLPo

I've read that you should have them inflated to the max PSI that reads on the sidewall as that is how they were designed to run.

So basically Im all over the place and my question is, can I run them at 60 or 65 PSI for an extended period (leaving for a 3.5 hour trip to Wisconsin on Friday) and not risk a blowout? I don't want to be that poor sap on the side of the highway changing out a tire. Although I always do bring the bag of tools with the impact in it and a floor jack to make a speedy change just in case.

Pics of said boat and trailer

 

[33 IMP]

I normally would have echoed the advice to run the max pressure that the tire says.
However, in your case, with stout tires and a light boat..... I'd set em to 55 cold, take a tire gauge along, stop for breakfast/lunch after 50 miles, measure tire pressure, and feel how hot they are.
Cool tire, at 60 lbs? I'd fly em as is. Are they warm? I'd put 75 in.

 

[Triplegreen500]

Why the hell do you have D's on a trailer that lightweight?

Get tires rated for the GVWR of the trailer. You should be running C's, tops, on that rig - and 35-50psi. Too low, it'll pogo; too high, and it slams in the bumps.

https://www.etrailer.com/dept-pg-Tr...ntent=Trailer Tires and Wheels - Load Range C

As light as that thing looks, you may want B's. Do your research.

Discount Tire | Tires and Wheels for Sale | Online & In-Person

 

[RemCharger]

Holy crap it's not a 1 ton, you could probably pick the back end up if you were pissed off lol. 35 -40 lb tops

 

[Don Frelier]

I would go even lower maybe 30 lbs

 

[Scott Engelhardt]

Do you have a lazer temp testing tool? If not you can get one most anywhere. Set the pressure where the boat doesn’t bounce then check the temperature after driving 25 miles. If the temperature is similar to the tow vehicle tires I would not worry about it. A high ply sidewall should be able to run a lower pressure when running a lighter load.

 

[Frank Mopar]

Max pressure has a weight that goes along with it. It’s not what you do.

Trailer tire pressure charts are readily available with a Google search.

 

[33 IMP]

Why the hell do you have D's on a trailer that lightweight?

Those look like the trailer wheel/tire combo sold at walmart. They probably came with D's.

 

[MarPar]

I bought D's because at that time, I could not find C's with an M speed rating. With the idiots around here, I wanted the ability to keep up/pass morons and not worry about overheating the tires.

And yes @RemCharger I have gotten pissed off enough to pick the back of the trailer up

Do you have a lazer temp testing tool? If not you can get one most anywhere. Set the pressure where the boat doesn’t bounce then check the temperature after driving 25 miles. If the temperature is similar to the tow vehicle tires I would not worry about it. A high ply sidewall should be able to run a lower pressure when running a lighter load.

I do have a laser temp gun. The first time I towed the boat+trailer after the trailer restoration, we went to a lake in Wisconsin about the same distance away as we are going on Friday and I checked the tires and hubs and a bunch of times (yes, Im that paranoid lol) and the tires at the highest were at 105* and the hubs at 115* at 70 PSI after an hour at 65 or so MPH.

 

[Frank Mopar]

Need to check tires across the tread and get three temps. High in middle let air out. Higher on edges put air in. Higher on one edge and lower on other it’s alignment issue.

 

[33 IMP]

I bought D's because at that time, I could not find C's with an M speed rating. With the idiots around here, I wanted the ability to keep up/pass morons and not worry about overheating the tires.

And yes @RemCharger I have gotten pissed off enough to pick the back of the trailer up



I do have a laser temp gun. The first time I towed the boat+trailer after the trailer restoration, we went to a lake in Wisconsin about the same distance away as we are going on Friday and I checked the tires and hubs and a bunch of times (yes, Im that paranoid lol) and the tires at the highest were at 105* and the hubs at 115* at 70 PSI after an hour at 65 or so MPH.

Tires (and asphalt) around here are way hotter than that, just sitting in the sun.
Imo, you'll be absolutely fine at 50-55 lbs.
California speed limits towing anything is 55 mph. Typical is around 62-65, but I see boats and trailers like yours frequently above 70.
Here in AZ, semi's are doing 85 on some of the crappiest highways I've ever seen. (I-40). 70 mph, and you'll find yourself and your trailer in a ditch!

 

[Daves69]

My old (sold by Sears) '67 Sportcraft Gullwing, bought in '86, came with only 5.30-12s IIRC.
I ran them @ 55-60 psi cold. Replaced every 3-4 years. Made lots of trips up to WI. One flat over 23 years on a trip up to Stevens Point. The floor jack and impact are your best friends!

 

[MarPar]

I reckon 55psi it is! Thank you Gents!