PC 2400 tire pressure question

I'm sure this has been discussed a bunch, and Jatrax has a similar post just ahead of mine; but my search hasn't really helped me much. . .probably because I'm somewhat on the dense end of the brain train.   The tire pressure label on the door of our 2400 Sprinter shows tire pressure as 61psi in all tires.  Our Cooper tires say max pressure is 80psi.  My forum search seems to say at near full loaded weight on a 2350 Ford E350 (similar size rig) rear duals should be at 65psi and front tires at 70psi.    

Are there any 2400 owners who might have a good idea as to what pressure I should shoot for?  Inquiring minds want to know!      

This might help: https://www.escapees.com/smartweigh/Cooper%20load%20and%20Inflation%20Table%20for%20RMT%20tires.pdf

Or confuse even more..................

   Thanks John, however the chart starts at 17.5" tires and our "Fawkes" has 16" wheels.  I used it when I had my Foretravel Class A and actually used the Smart Weigh folks at an Escapees rally years ago.

The previous owner did put all new tires on Fawkes just a few months before we bought him.  They're Cooper Discoverer HT3 LT215/85/16 Load range E tires.  The max load single is rated 2680 lb @ 80psi; and the max load dual is rated 2470 lb @ 80psi.  I just had the valve extensions completed yesterday, and the shop inflated all 6 tires to 80psi.  The pic is the door label.  All these numbers and various observations make getting the pressure right for my new Tire Traker TPMS "curiouser and curiouser"!       

I was fortunate to find a Michelin chart that had my tires on it so that has helped.  Still confusing but as I understand it the 80psi is the maximum you should inflate to.  If going by the weight you can use less air but you need the chart to do that.  But I'm still researching and hoping someone can explain this to me in small words.

Try this: http://tiregroup.com/wp-content/uploads/2013/09/2014_Cooper_Product_Manual.pdf Page 44-45 I think.

Thanks again for the Cooper link.  It does give all the technical information about my tires, but at the page's end, the quote is: "Use the information on the vehicle placard and vehicle owner's manual to identify original equipment inflation pressure, tire size, speed rating and load carrying capacity."  So, according to my vehicle placard, I should not exceed 80psi, but the recommended pressure for the listed weights (on the placard) is 61psi.

Reading your discussion on this same page, I'm wondering, what does your vehicle placard show as recommended pressure(s)?   

Both the Ford and the PC plates call for 75psi front and 80psi rear.

However, they list the weight as 5,000# front (so 2,500# per tire) and 9,600# rear (so 4,800# per dual pair).  I take that to mean that at full GVWR the tire pressure should be 75psi front and 80psi rear.  But I'm not at GVWR.  So I am assuming that the placard rating is CYA in case you are fully loaded up to GVWR.  If you go over that you are on your own.

But under that weight I do not know what should be done.  Go with the tire inflation charts?  Still confused.

I only have the Mercedes Benz Sprinter plate. . .no PC plate found.  I got on the Sprinter forum, and the answers are as confusing as the PC forum.  I sent an email to Kermit to see if he will chime in on this issue.  Since you are dealing with a Ford chassis and I'm dealing with a Sprinter; we may have an apples/oranges situation.  And, the beat goes on. . . . .

It's not a matter of which chassis you have, it's how much weight you are carrying. The tire sidewall gives the maximum pressure to get the maximum load capacity for the tire. The pressure you need is whatever will carry the load you have, thus 61 lbs. would be correct if that is what the tire needs for the weight it carries. If you know what the weight is the tire must carry, you can look in the chart for that tire and find a pressure that will work. The charts usually are in 5 lb. pressure increments so go with the next pressure above what your weight is.

Hope this helps.

It's not a matter of which chassis you have, it's how much weight you are carrying. The tire sidewall gives the maximum pressure to get the maximum load capacity for the tire. The pressure you need is whatever will carry the load you have, thus 61 lbs. would be correct if that is what the tire needs for the weight it carries. If you know what the weight is the tire must carry, you can look in the chart for that tire and find a pressure that will work. The charts usually are in 5 lb. pressure increments so go with the next pressure above what your weight is.

Hope this helps.

I'm not sure what chart you are referring to.  Cooper tires doesn't publish one; in fact they say, "Use the information on the vehicle placard and vehicle owner's manual to identify original equipment inflation pressure, tire size, speed rating and load carrying capacity".  So to sum up all the vague discussion points, it seems like that is my answer to what tire pressure should I use.

I'm not sure what chart you are referring to.  Cooper tires doesn't publish one

I don't think that is correct.  Cooper does publish a chart. See here: http://tiregroup.com/wp-content/uploads/2013/09/2014_Cooper_Product_Manual.pdf Page 44-45 I think.

What is printed on the vehicle sticker is for the GVWR.  So if you are fully loaded to max weight or do not know the weight, use what is on the sticker.  If you know the actual weight use that and the chart.

Here is some information from Goodyear: http://www.goodyearrvtires.com/tire-inflation-loading.aspx  Here is a portion of that page that sums up what I am talking about:

The recommended maximum inflation pressures for your tires are indicated on the certification label or in your owner's manual. Since RVs can be loaded with many different configurations, the load on each tire will vary. For this reason, actual air pressure required should be determined based on the load on each individual tire. Inflation pressure should be adjusted to handle the tire carrying the heaviest load, and all tires on the axle should be adjusted to this standard.

For my rig the max is 75psi front and 80psi rear but from my recent weigh I have 2,450 on the heaviest side up front and 4,300 on the heavy side in the rear.  So from my Michelin chart that works out to 70psi front and 65psi rear.  I think upping the rear to 70psi in case of dynamic load is prudent.  But that is still a good bit below the 80psi maximum the tire will stand.

Thanks again John.  I've bookmarked both the Michelin and the Goodyear charts.  Bumped your neighborly button again.   

Hi THIAC,

I had just replied to jatrax's tire pressure question so I will just quote it here for the heck of it.  It might be more applicable to you given we have the same PC model.

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jatrax,

We have different PC models, you with a 2552 and me with an old 2350 so keep that in-mind.  Yet I think much can be applicable.

Our 2350 is of the earlier design where the fresh water tank is butted across the rear wall.....the worst for weight distribution, and because the water sloshes side-to-side, it affects handling.  Amplifying the situation is our 158" wheel base.  We successfully addressed the handling issues with aftermarket suspension upgrades, but the tire pressure remains a gray topic.

The PC sticker on our driver door frame states 65psi front, and 60psi rear(65/60).  After weighing our rig loaded up on a big trip, the Michelin charts recommends the same psi.  So at least we have that consistency.

My concern is the when I put the recommended 65/60psi, it looks like there is not enough air in the tires.  They look under-inflated with significant bulges where the tires meet the road, the rear tires worse than the front.  I have to add 10 additional psi 75/70 before the tires look right, but doing so roughens the ride terribly.  So like others here, I too have added just 5psi to the specifications 70/65 as a compromise.  Sometimes I run 65/65 depending on what we bring along.

I think you are doing great having only a 275 pound difference between one rear corner and the other.  I don't know what our corners weigh for I weighed just the axles, but I anticipate a significant difference given the placement of our fresh water tank and outdoor storage compartment.  One thing you don't want to do is have varying tire pressures within an axle.  Take the worst case rear corner and make the other rear corner psi match it.

When you figure it out, be sure to educate me for every we leave home, I feel I didn't get it right yet again.