Tire pressure - check my math please.

[k.darwin]

Micro Minnie. 3900 lbs dry, I estimate 4500 lbs or less for a weekend trip. Four tires, each rated at 2040 lbs at 65 psi.

2040 lbs divided by 65 psi = 31.38 lbs-load / psi

4500 lbs trailer divided by 4 = 1125 per tire. Add 30% for dynamic margin = 1462 lbs.

1462 lbs per tire / 31.38 lbs per psi = 46 psi. Hmm, seems a bit low.

Add 10 psi for "over 65 mph travel" (though I'll be running 65 or less) and then round up to 60 for extra margin.

I don't want a blow-out due to under inflation. Nor do I want a rock hard tire that has no give so that any road hazard takes it out.

60 psi. Good or bad? :-)

[BobC]

Do yourself a favor and weigh it. I never weighed either of my TT but weighed my new-to-me 2002 motorhome for the first time the other day. Easy Peasy, went to the truck stop, drove on, got weighed for $11. Now I know exactly where I stand. I wish I'd done so with my TT, who knows how close I was.

Weigh it with full propane, full freshwater tank and your expected load of stuff. The scale is segmented so make sure your trailer isn't in the same segment as your truck.

Take a broomstick to push the buttons with, their at 16-wheeler driver height.

[k.darwin]

Yes, weighing it is on the list, but this trip we don't go past the scale.

I weighed my Winnie Drop and the weight came within a couple hundred pounds of the literature. Except for hitch weight which was 100 more than stated.

I've already weighted the hitch on my new trailer and sure 'nuf it is higher than the literature (490 vs 360).

[old_engineer]

I just fill them to the pressure on the sticker and have never had a problem. You also need to take into consideration the max pressure for the rims and valve stem as I recall.

[sd75mac]

Went with a load range "E" and high pressure metal valve stems, running at 65psi. No worries.

[Tucsontoy]

You are making it more complicated than it is. Lets say your trailer is a dual axle and it weight is 4000 lbs. That means each tire should be rated for at least 1,000 pounds. Read the rated weight on the sidewall. It wil be greater than 1,000 pounds. The air pressure be kept at the recommended pressure all of the time.

[BobC]

It's a bit simpler with a travel trailer. With a motorhome, inflating to the "sticker" pressure assumes maximum load, which is OK but, if you're significantly below max load, can result in a rough ride.

[LarryW]

I believe you know less than the tire manufacturer. I do. Inflate to max pressure indicated on sidewall.

[k.darwin]

Well the sidewall number is the max for the tire to achieve max load carrying capacity, not the recommended pressute for any specific vehicle. My P-metric truck tires are sidewall rated at 51 psi but the vehicle manufacturer recommends 30 psi.

[LarryW]

We were speaking of trailer tires. Not cars, trucks or motorhomes.

[old_engineer]

The sticker on my 2106FBS recommends 50 lbs for the tires which is what I set them to even though the sidewall says 65 lbs maximum. There is more to the recommended pressure than the tire capabilities themselves and I figure the manufacture has a better handle on that than I do.

[LarryW]

I too figure the tire manufacturer to know their tires, and the tire manufacturer says 65. Please recheck the sticker for Load Range C which are 50 PSI. LD Ds are 65.

[LarryW]

And, old engineer, note this source, a seller of TT tires...

https://www.etrailer.com/question-74760.html and

[old_engineer]

I don't care what etrailer says they aren't going to be liable should anything go wrong nor will they back you up with the manufacturer if you have a problem attributed to over inflation which isn't just the side wall rating but the manufacturer recommendation. Your free to so as you wish as you have to live with the consequences just as I do with my decision. Until then I will advocate using the sticker with tires that meet the OEM specification on OEM rims.

[LarryW]

See page six for Winnebago’s recommendation on PSI for Load Range D trailer tires.

http://winnebagoind.com/resources/ma...wnerManual.pdf

[LarryW]

“I don't care what etrailer says...”

A retailer of travel trailer tires recommending an inflation pressure IS liable if their recommendation is followed and wrong. Conversly, they ar3 not liable if their recommendation isn’t followed and an issue occurs.

So now I’ve shown you the recommendation of etrailer and Winnebago for Load Range D rated tires...

[BobC]

Here's a site maintained by Roger Marble, a retired tire engineer who posts on IVR2 as Tireman9. The link I've given is to an interesting trailer-specific article but if you go to his home page, there are links to a lot of pertinent info:

RV Tire Safety: Search results for trailer

Anecdotal information from those of us who aren't experts in the field isn't as good as that from an expert who has a much broader, better informed and balanced perspective.

[LarryW]

Please note what America’s Tire Store says at https://www.americastire.com/learn/trailer-tire-faqs

First “check” mark. “A trailer tire should be inflated to the maximum inflation designated on the sidewall of the tire to provide the full load carrying capacity”

[LarryW]

Fifth Wheel Street has modified their recommendation. See Step 4 - RV and Tow Vehicle Tire Inflation Procedures | Tire Load Charts

“We at Fifth Wheel Street no longer recommend adjusting trailer tire inflation pressure below the pressure associated with maximum load PSI rating molded on the sidewall...”

[LarryW]

West Marine has a pretty good reputation. See https://www.westmarine.com/WestAdvis...er-Tire-Basics

“Maintain pressure at the maximum PSI recommended on the tire’s sidewall for cool running, load-carrying ability and lowest rolling resistance.”