RV Manufacturer versus Tire Company air pressure settings

More To See wrote:
Let's try this again.

That tire pressure plate on your door only applies to a brand new rig straight out of the factory on day one with original tires. After that in later years it is likely meaningless.

For the vast number of older rigs running after market tires it simple can not be trusted.

But if in fact that door plate remains true for ever and ever then why not just tell any poster asking about tire pressures to just go look at their door plate.

If it's that simple then why is it that threads about tire pressure go on and on for page after page all the time.

Doesn't it always come down to "weigh each wheel" etc, etc.

Nobody ever says "go look at your door plate."

For all those out there in a rage that I suggest not to rely on those door plates I sure hope to never catch any of you looking at a tire pressure chart. On second though, why are they even published.

Wrong again! And more BS!
Regardless of Manufacturer, tires of the same size and load rating require the same pressure. So, provided the tires on the used rig are in fact the same size and load rating as the originals, the OEM pressure labels will still apply.
Did you really believe vehicle manufacturers of all types have different tire pressure values applying to different tire Manufacturers? (Assuming the same size tires)

Of course, if the tire sizes have changed, it's a whole new ball game. Then it's time to break out the load/inflation tables.

rtz549 wrote:
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So an RV maker buys one of these:



The sticker on it says pump them up to 70psi. They get done building it and now it weighs 30,000 lbs or more. Your driving across death valley and you've got 60 psi in your tires. Same story. Should have had 90 psi or more in them.

Semi Trucks don't mess around with trying to run the least amount of air for a smooth ride. If the tire will take 110 psi; that's what's in it.

I think the entire RV industry as a whole would have far fewer blowouts and tire issues if all tires were set at max PSI. Safety margin, less flexing at speed. If you read the fine print in the pdfs for semi truck tires; there is a statement that says something to the extent of if you will be running at speed at max load; run an extra 10psi in the tire.

You apparently do not understand the process by which the tire pressures are determined for a vehicle that is built as a chassis with the body added by a secondary Manufacturer.
The chassis builder DOES NOT GENERATE ANY TIRE PRESSURE DATA
The finished vehicle is certified by the final stage Manufacturer (in our case, the RV builder) and it is he who determines the required tire pressures to support the final vehicle axle ratings and HE produces the Certification label with weights and the label with tire pressures on it.
As to your argument about setting tires to max pressure regardless, talk to some tire experts about center tread wear, reduced braking capacity, reduced water displacement on top of the harsher ride.

I always recommend 5 to 10 psi cold over the GVWR sticker not to exceed sidewall max.
Cold is before driven and before the morning sun hits the tires.
Assumes you have same size and load rating as the sticker.

Let's try this again.

That tire pressure plate on your door only applies to a brand new rig straight out of the factory on day one with original tires. After that in later years it is likely meaningless.

For the vast number of older rigs running after market tires it simple can not be trusted.

But if in fact that door plate remains true for ever and ever then why not just tell any poster asking about tire pressures to just go look at their door plate.

If it's that simple then why is it that threads about tire pressure go on and on for page after page all the time.

Doesn't it always come down to "weigh each wheel" etc, etc.

Nobody ever says "go look at your door plate."

For all those out there in a rage that I suggest not to rely on those door plates I sure hope to never catch any of you looking at a tire pressure chart. On second though, why are they even published.

Regarding my tire pressures, fully loaded I run right at GAWR and I increase the Bridgestone recommendations by 5 or 10 psi as a buffer. And yes my door plate says 65 psi front and rear. And I am running the original rims and tire size. My Bridgestone chart does not even start until 70 psi.

enblethen wrote:
Here in Washington, you can go into any truck weigh station when it is closed and weigh the rig.
There is enough room to weigh each corner.
Most commercial scales are not wide enough.

I assume you are talking about the weigh stations along the Interstates? If that's affirmative I presume that watching for a closed station and then pulling out to it will give me the chance to check the corner weights?

Here's my beef with those door stickers and recommended pressures. In passenger vehicles in particular; they build them with 1" - 3" of total suspension travel and they ride like chuck wagons and then try and get the rest of the suspension travel / ride comfort out of the tires by putting 32 lbs of air in them. So the weather changes and your crossing death valley in the summer time and your tires are at 25 lbs. Maybe you'll make it across. If the tires max out at 60 psi; I'd feel a lot better with 60 in them.


---

So an RV maker buys one of these:



The sticker on it says pump them up to 70psi. They get done building it and now it weighs 30,000 lbs or more. Your driving across death valley and you've got 60 psi in your tires. Same story. Should have had 90 psi or more in them.

Semi Trucks don't mess around with trying to run the least amount of air for a smooth ride. If the tire will take 110 psi; that's what's in it.

I think the entire RV industry as a whole would have far fewer blowouts and tire issues if all tires were set at max PSI. Safety margin, less flexing at speed. If you read the fine print in the pdfs for semi truck tires; there is a statement that says something to the extent of if you will be running at speed at max load; run an extra 10psi in the tire.

Too many questions/concerns about how much air. All the way and that's the best that can be done. If they are pumped up all the way; what more can you do? At least they aren't under inflated.

Here in Washington, you can go into any truck weigh station when it is closed and weigh the rig.
There is enough room to weigh each corner.
Most commercial scales are not wide enough.

The subject has fortunately been as educational as it has become entertaining- I have a followup to the original question- there's been a lot of suggestions of determining the weight on each corner- where exactly would I be have the opportunity to have that measured?

Dale.Traveling wrote:

More To See wrote:
Right now my door plate recommends 65 psi front and rear but I have to run 95 psi front and rear per Bridgestone for my weight. And I'm not overloaded.

Are you sure about your numbers? Bridgestone 8R-19.5 tires inflated to 95 psi have a combined load capacity of 18,390 pounds (per Bridgestone's inflation table). A 1995 Winnebago Vectra 34 built on a P30 chassis has a GVWR of 16,500 pounds (per Winnebago's' literature). That puts you at 1890 pounds in excess of the chassis designed limits, as long as Winnebago's information is correct. Not easy to find chassis info going back 20 years.

Hmmm, mebbe the real picture is starting to emerge perhaps?:R

wolfe10 wrote:
Boy, this thread has run the full range from accurate to bizarre.

FACT: The GVWR sticker installed by the coach manufacturer is for the OE tires (yup, they DO know what they put on there) when loaded to GAWR.

Please provide facts that are contrary to this statement.

And, no, I would never suggest any method of accurate tire pressure determination without weighting each wheel position. Then, take the heavier wheel position on each axle to determine the correct minimum PSI for all tires on that axle from your tire manufacturers inflation table.

Unlike car tires, the correct PSI for the tires on our coach (per Michelin, not me) is 70 or 110 DEPENDING ON LOAD. That is a huge range and over or under inflating is quite likely if you don't know your actual weights.

The placard installed on our 2001 Winnebago Adventurer reflected the recommended tire pressure for the tires originally installed on the vehicle. It came with a placard indicating the minimum tire pressure should be 70 psi. About a year after we purchased it Ford sent a certified letter with a new placard recommending the minimum pressure be increased to 75 psi. Also included in the letter was an updated placard raising the lug nut torque from 140 ft. lbs. to 160 ft. lbs.

The motorhome came with Goodyear G670 tires size 245/70R19.5. The Goodyear load and inflation table recommended a minimum of 70 psi for tires built before 2002, and 75 psi for those built in 2002 and later. Since tires built before 2002 would now be a minimum of 13 years old that spec is no longer mentioned in the table. The latest version of the table recommends a minimum inflation of 75 psi.