RV Manufacturer versus Tire Company air pressure settings

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.

wolfe10 wrote:


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.

Wolfe10 is on target with his post.. I would add in addition to weight the tire pressure is determined by make and tire model, tire size and whether single or dual position.


As was pointed out know your weights, and inflate according to tire manufacturer specification for model, tire size, and tire position

JohnnyT

Lady on the phone told me that I could use LESS pressure all around, but if I was happy with 80 all around (all 6) no problem.

I would never ever believe a lady on the phone about air pressure on my diesel pusher motor home NEVER

Call the tire manufacturer.
All have helpful customer service.

More To See wrote:
Those plaques the RV manufacturers put on vehicles spelling out tire pressures are absolutely dangerous....

We obviously have a major disconnect in our views.
I still submit yours is a dangerous perspective.

I would love to see a copy of your tire placard, a weight ticket for your rig and your tire info so we can try to figure out what's going on in your case.
I see no way you have such a pressure discrepancy UNLESS you have installed a narrower tire than OEM, but with a higher Load Rating.
OR
Your rig Manufacturer did in fact get it wrong, which is unlikely given the legal consequences.

Show me I'm wrong!

More To See wrote:
Those plaques the RV manufactures put on vehicles spelling out tire pressures are absolutely dangerous.

Pretty bold statement to make. If true there would be some pretty rich personal injury lawyers and probably no or a very small RV industry. Not only would the coach builder be in the subject to legal action but the chassis manufacture, tire manufacture, throw in the axle manufacture and for good measure who ever drove the coach from the builder to the dealer.

The placard numbers are based on the tire size and load group, which is also listed, against the axel load limits. Over load a coach or change tire size or load group from recommended and you're on your own.

More To See wrote:
I stand by my posting.

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.

And in every past post I can remember from others they see the exact same thing. A very low recommendation of what tire pressure to run.

May I just refer back to the OP today. How far down the road would he get running those door post pressures?

On edit: assuming this isn't a brand new rig straight out of the factory.

And I stand by mine!
Had I done otherwise I would have been in jail and my employer would have faced a $10,000 fine for every vehicle with incorrect information!.

If you are running OEM size tires on a rig that is NOT overloaded, there is no way there is a 35psi difference between what the Manufacturer stated and what the load/pressure tables say.
If you are running different tires from OEM spec, you are on your own and SHOULD use the load/pressure tables.

To reiterate - the ONLY time you should run sidewall MAXIMUM pressure is when the tire is carrying its MAXIMUM rated load.

Folks running their rig within its weight ratings at tire placard pressures on OEM size tires are NOT underinflated and will run down the road just fine.

To state otherwise is just plain WRONG!

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.

What he said was get the four corner weights and then use the tire manufactures psi charts. Based on the weights you record you set the psi. It could be lower, the same or higher. Front normally higher than rear based on tire manufactures psi charts.

Jackie Treehorn wrote:

wolfe10 wrote:
NO, the PSI on the GVWR sticker (usually by the driver's area) indicates THE CORRECT/MINIMUM PRESSURE WHEN EACH AXLE IS LOADED TO ITS GAWR.

Hopefully, your actual weights will be well under GAWR and therefore the correct/minimum PSI will be less.

The 70/75 psi levels are from the GVWR sticker. You're saying that if I'm traveling with no water I would actually go lower than the 70/75?

23hotrodr wrote:

More To See wrote:
Those plaques the RV manufactures put on vehicles spelling out tire pressures are absolutely dangerous. But I think they are required by the feds.

With not a clue in the world of what tires you are running on your rig how could they possibly be able to tell you what air pressures to run with.

How many rigs are out there right now running down the road with severely under inflated tires because somebody use those stupid plaque recommendations?

Perhaps a little work with a hammer and chisel might save some lives.

This is one of the most ridiculous replies I have ever read here! Winnebago knows exactly what tires (load range) they are installing and the maximum loads per axle the coach is designed to carry. They use these figures to determine the tire pressures on the plackard.

Please know what you are talking about if you wish to be helpful in the future.

that *might* be true for tires delivered on a brand new MH but it would be coincidentally true at best when buying a used MH. in both cases it is best to know for sure rather than guessing and hoping for the best by weighing the MH as it is loaded for travel and inflating the tires per the mfg chart.