Recommend Tire Pressure

[Red-Rover]

Please recommend a tire pressure for my 5th wheel, tandem axle.
Tire size is 235-80R-16 , Rating is E , Max pressure is 80 PSI.
By actual scale weighing, the four trailer tires share a load of 8180 pounds plus maybe another 600 pounds for food and water?
Getting frustrated looking for a recommended table on line and decided to go to the people that know the answer.

[Vulcan_Rider]

JIMNLIN wrote:


'Unless trying to resolve poor ride quality problems with an RV trailer, it is recommended that trailer tires be inflated to the pressure indicated on the sidewall of the tire.

So it isn't ALWAYS REQUIRED.

And taking that statement as gospel ASSumes that the vehicle still has the original spec'ed tires on it.

This discussion started out asking about upgraded tires.

[Vulcan_Rider]

4X4Dodger wrote:

That is exactly how they are spec"ed as there is no other datum to spec to.

Secondly IF you run the tires at the cold pressure inflation on the sidewall you will always be in line with the tire's warranty. You will not be if you run under that.

Using some chart on the internet to determine tire pressure that can be disavowed by the tire MFG and the Trailer MFG is not a smart approach.

You aren't addressing what I am saying but just spouting the same thing over and over. Exactly WHAT is "how they are spec'ed" ??

And your assertion about the tire warranty is absurd.
90% of the vehicles on the road have manufacturers recommendations that are UNDER the max. load pressure and that DOES NOT NEGATIVELY AFFECT THE WARRANTY. The vehicle makers aren't going to take a chance like that.

And for the third time, I and not saying you should "use some chart on the internet" unless it comes directly from the tire manufacturers site.

Blindly recommending using the Max. stamped on the sidewall is not a smart approach. The fact that you get away with it doesn't change that.

[jadatis]

A reasoin not even to trust the tire makers, is that monney is involved.
If TT- or 5thwheel- maker would have to put LT tires under them , they would need, or larger tires, or higher loadrange tires wich are more expensive for them, and their proffit is less. That is why tire makers make ST tires , wich to my opinion is yust slightly different then LT , but calculated in their maximum load for lower speed so more deflection allowed.
Then with a cheapeer tire for the TT maker the GAWR is covered .
But using exact calculated pressure for the GAWR , or considdering an unequall load R/L, would still give the tire more deflection so more heatproduction so less fuel economy , and most important lesser reserve and by that more tire failure.

That is why they stronly advice to use maximum pressure of tire , to give most tires the reserve they need so lesser tire failure.But because mostly the tires bare yust enaugh to cover the GAWR, this max pressure of tire is mostly not even enaugh, and still tire failure.

Then they give waranty only on the tires and then even less for the years you used them. The damage to your TT or 5thwh is not payed.
Yust to avoid further claims.

[JIMNLIN]

You are absolutely welcome to your own opinion but I will stick with what the real experts recommend, that being the tire and vehicle makers and not someone on the Internet likely with no real engineering credentials at all.

Here is a quote from Goodyear RV tire website; goodyear.com
Goodyear Tire and Rubber .... weighing RVs
Special Considerations

'Unless trying to resolve poor ride quality problems with an RV trailer, it is recommended that trailer tires be inflated to the pressure indicated on the sidewall of the tire. Trailer tires experience significant lateral (side-to-side) loads due to vehicle sway from uneven roads or passing vehicles. Using the inflation pressure engraved on the sidewall will provide optimum load carrying capacity and minimize heat build-up."

And from Carlisle ST tire warranty pages; http://www.carlisletransportationproducts.com/product/tires/trailers-toy-haulers-towables/radial-tra...carlisle.com
-Maintain air pressure at the maximum PSI recommended on the tire sidewall.
and
"The Warranty is void if the tire or wheel fails due to damage from improper inflation pressures, exceeding the maximum speed limit, or overloading the tire beyond the maximum load capacity stated on the sidewall.

Vehicle experts ?? I assume your thinking RV trailer builders are some kind of experts on tire design or assume they can or will choose the best tire for their trailering customers.
IMO trailer mfg haven't proven to be the best source for tire choices/tech recommendations.

[Vulcan_Rider]

4X4Dodger wrote:

That is exactly how they are spec"ed as there is no other datum to spec to.

Using some chart on the internet to determine tire pressure that can be disavowed by the tire MFG and the Trailer MFG is not a smart approach.

If your trailer differs...how do you know that isnt a mistake? Whereas the molded in tire inflation on the tire is definitely reliable.

I don't understand that first sentence. The trailer/RV manufacturer uses the gross vehicle weight to decide what tires to put on it and what pressure to recommend. It is NOT always the max. on the sidewall.

I never said or even hinted at using ANY figure other than the one the manufacturer supplies. Go a little bit higher, maybe 5 pounds, sure no problem. Going 10 or 15 or 20 higher than the recommendation; probably no problem for the tire but other things might suffer.

And you are just being ridiculous with that last statement. How do you KNOW that the number stamped into the sidewall might not be a mistake ??

And lastly, to go back to what started this "discussion", if you increase the load range of the tires there is absolutely NO reason to also increase the inflation pressure.

What if a guy wants to REALLY increase his margin for error and upgrade TWO load ranges......starting with a C on a small unit with maybe 55 PSI and upgrading to an E where the sidewall might say 100. Are you really recommending that he put 100 in his new tires......REALLY ??

You are absolutely welcome to your own opinion but I will stick with what the real experts recommend, that being the tire and vehicle makers and not someone on the Internet likely with no real engineering credentials at all. There is no disrespect intended in that statement.

[4X4Dodger]

Vulcan Rider wrote:

4X4Dodger wrote:

The inflation on the sidewall is the correct cold inflation pressure and the tires are sized and speced for the vehicle.

You are ASSuming that the tires were spec'd to run at their max. load and max. pressure and that might NOT be the case.

If they were over-spec'd, it might be better overall to run them at slightly less than the number on the sidewall. Over-inflated tires are not likely to suddenly fail but, depending on the specific tire, they might have slightly less traction and will make for a rougher ride and more strain on the suspension.

If the tire type has been changed.....for instance, the originals had a max. pressure of 80 and the new ones have 100.....it is NOT a good idea to run them at 100. Hit a big pothole and break your shock mounts......or worse.

That is exactly how they are spec"ed as there is no other datum to spec to. Secondly IF you run the tires at the cold pressure inflation on the sidewall you will always be in line with the tire's warranty. You will not be if you run under that.

Using some chart on the internet to determine tire pressure that can be disavowed by the tire MFG and the Trailer MFG is not a smart approach.

In most cases you will find like my trailer that the two numbers match. The sticker tire inflation is the same as the tires. If your trailer differs...how do you know that isnt a mistake? Whereas the molded in tire inflation on the tire is definitely reliable.

Do what you want but you cannot go wrong with what is on the sidwall and there is definitely no need to weigh the trailer to decide this.

[Vulcan_Rider]

4X4Dodger wrote:

The inflation on the sidewall is the correct cold inflation pressure and the tires are sized and speced for the vehicle.

You are ASSuming that the tires were spec'd to run at their max. load and max. pressure and that might NOT be the case.

If they were over-spec'd, it might be better overall to run them at slightly less than the number on the sidewall. Over-inflated tires are not likely to suddenly fail but, depending on the specific tire, they might have slightly less traction and will make for a rougher ride and more strain on the suspension.

If the tire type has been changed.....for instance, the originals had a max. pressure of 80 and the new ones have 100.....it is NOT a good idea to run them at 100. Hit a big pothole and break your shock mounts......or worse.

[Learjet]

http://www.maxxis.com/trailer/trailer-tire-loadinflation-chart

[Vulcan_Rider]

JIMNLIN wrote:

Check out the two sources (CapriRacer/Tireman9) you left out of my reply ......

And what exactly makes those sites "authoritative" references on this subject ??

They both look like sites created by some individual; more self proclaimed experts. Are they even sites; guess I need to go back and look at your last post to see what you are trying to say.

I don't think following the vehicle maker's recommendations exactly qualifies as "ignorant".

[4X4Dodger]

Ranger Smith wrote:
You really need to get it weighed to get the proper inflation for the weight

Sorry but I must say "BS".

The inflation on the sidewall is the correct cold inflation pressure and the tires are sized and speced for the vehicle. There is no need to weigh it.

Running at the max inflation will help insure that you don't blow one out due to underinflation and heat build-up.

[JIMNLIN]

I'm sorry but I don't trust most of what I find posted on public sites.

Check out the two sources (CapriRacer/Tireman9) you left out of my reply .......and educate yourself on the subject if you don't want to take advice from other RV.net folks.

[Vulcan_Rider]

JIMNLIN wrote:

IMO what makes the most cents/sense is to listen to hundreds of experienced trailer owners

and see what real tire engineers/experts have to say on the subject of tire pressure for a trailer.

Yep. Anecdotal subjective opinions are always better than what the professional engineers who work for the trailer makers just pull out of thin air. (Sarcastic mode off)

IF you are completely in the dark about what to do......the best place to START is with what the manufacturer suggested.
After that, it's a matter of who you trust.

I'm sorry but I don't trust most of what I find posted on public sites.

[JIMNLIN]

Vulcan Rider wrote:

fla-gypsy wrote:
Trailer tires should be ran at max pressure listed on sidewell to generate greatest reserve capacity with few exceptions. Nothing else makes much sense

What makes the most sense is to find out what the manufacturer recommends.

Is that not really available for every rig ever make.....REALLY ??

IMO what makes the most cents/sense is to listen to hundreds of experienced trailer owners who have hundreds of thousands of miles and several different trailers or simply look in on tireman9 tire blog or CapriRacer (Barry Smith on allexperts.com) and see what real tire engineers/experts have to say on the subject of tire pressure for a trailer.

[jadatis]

The sise indicates ST tires wich are given maximum load for up to 65m/h.
then more deflection then a LT tire of same sises would have , wich is not in the market, comparable is LT 235/85R16 .
But to show why you can use 80 psi and still will have no bumping or centre wear , you can read next topic started by me.

In last posts even spreadsheet to make your own list and filled in with max/min load on tire

If then questions or you want me to help , ask it here.

Once read that tires are tested to can stand 2 to 3 times the AT-pressure ( yours E-load 80 psi) so even when filled with cold higher pressure , wich most brands allow up to 10 psi, at freesing point of water , and temp inside tire rises to boiling point of water , the tire wont reach that 2 to 3 times AT-coldpressure.

Not even when its in fact a D-load constructed tire wich is set in the market as E-load, wich I suspect is often done in America, to fullfill the American dream of bigger is better.