Weighed RV , what tire pressure?

[martz]

I have finally weighed my motorhome.
2016 fleetwood storm 35sk.

It has the f53 22000lb chassis
Goodyear 245-70-19.5 tires. It was fully loaded including a full tank of gas and fresh water. (I always travel with full water)

I got it weighed at a pilot cat scale for $11.50.

front axle 6620lbs
rear axle 12640lbs


I have been running at the sticker recommendation (95psi) until I had a chance to weigh it.

The goodyear chart says 80psi , is that too low or should I just go up to 85 to be safe?

Thanks

[Waiter21]

The pressure listed in the tire chart is the MINIMUM for that weight. On my Southwind, the Cooper/Roadmaster tire chart tells me front 70, rear 80 psi .. I run all 6 tires at 85 psi.

[Jim_HiTek]

When I owned my '94 Bounder, that had 19.5 tires, I always ran them near to the max rating stamped on the tire. This was to help with stability. Over 12 years of ownership the rears always did excellent, all the tires wearing at the same rate. The fronts did seem to wear oddly but I always got the mileage expected from the brands I used so that never mattered.

However, running them at higher pressures can make the ride harsh under certain road conditions but that never bothered me...

[Sweetbriar]

95 is what you'll need for axle capacity. 80 is good for what the coach weight was the moment you drove across the scale and does give you a bit of wiggle room but don't try and noodle the chart below 80. Consider 80 your minimum.

The problem is a coach has a way of packing on the weight without you knowing it. A case of water here, a tool kit over there, and new multi burner grill, campfire in a can and the next thing you know the coach just picked up an extra 1000 lbs. Granted the inflation charge is probably conservative but why tickle the dragon's tail. Run 85 which gives you 860 lbs front and 1420 rear excess capacity from your current weight.

Now if your Navigator starts collecting rocks on your next summer vacation outing take pressures back up to 95.

[wildtoad]

From your weights, I would run the 80. You are actually under the minimum so go with the first number in the chart.

[Domo]

Originally Posted by Waiter21

The pressure listed in the tire chart is the MINIMUM for that weight. On my Southwind, the Cooper/Roadmaster tire chart tells me front 70, rear 80 psi .. I run all 6 tires at 85 psi.

The pressure on the chart is the MANUFACTURERS RECOMMENDED pressure for the weight.

The only reason to add 5 PSI would be to compensate for not having four corner weights, therefore, one side of the axle could be a few hundred pounds heavier than the other. (Hopefully, not more than that, else the chassis mfg. would be upset as well.)

Even with four corner weights many owners add 5 PSI because they know better than the tire manufacturer's engineers or think they may shift their loads by several hundreds pound quite frequently, or that's the way they've always done it and never had any trouble, or something...

I run mine at the recommended chart pressure after having discussed it with a couple of Michelin (my tires) factory reps. Not being at the recommended pressure simply does not help the tire, tire life, ride comfort or traction.

However, as with all things, it's your gear and we all wish each other luck on highways and byways.

[Domo]

Originally Posted by Sweetbriar

95 is what you'll need for axle capacity. 80 is good for what the coach weight was the moment you drove across the scale and does give you a bit of wiggle room but don't try and noodle the chart below 80. Consider 80 your minimum.

The problem is a coach has a way of packing on the weight without you knowing it. A case of water here, a tool kit over there, and new multi burner grill, campfire in a can and the next thing you know the coach just picked up an extra 1000 lbs. Granted the inflation charge is probably conservative but why tickle the dragon's tail. Run 85 which gives you 860 lbs front and 1420 rear excess capacity from your current weight.

Now if your Navigator starts collecting rocks on your next summer vacation outing take pressures back up to 95.

You always get your weights when fully loaded for travel - otherwise it's just guesswork, as you've implied.

[Sonic]

Originally Posted by Domo

The pressure on the chart is the MANUFACTURERS RECOMMENDED pressure for the weight.

+1 It's recommended pressure, not minimum.

[Gary RVRoamer]

Minimum or recommended is nitpicking, I think. Whether you call it minimum or recommended, it's what you need for that weight. The concern is that the actual weight on any given day may well be higher, whether it's because you added some load or because you estimated wrong (no four corner actual). If the weight is higher than what you used in the table look-up, then the psi will be insufficient. For that reason, best practice is to go 5 or even 10 psi above the inflation table value, thus assuring you are NEVER underinflated.

[Sonic]

I see it differently. "Recommended" is the ideal pressure and that there's room to safely go a little lower if the tires were to lose a little air between filling. Calling it the "minimum" suggests that you cannot safely go lower than the stated pressure, causing people to add to that number and potentially overinflating the tire. Just my thoughts on the terminology.

[MSHappyCampers]

Hi ! Welcome to IRV2! We're sure glad you joined the gang!

Noticed you are kinda new on IRV2 and wanted to say hello!

I add 5 PSI to the recommended pressure! Have fun and keep her between the ditches!

Good luck, happy trails, and God bless!

[Domo]

Originally Posted by Gary RVRoamer

Minimum or recommended is nitpicking, I think. Whether you call it minimum or recommended, it's what you need for that weight. The concern is that the actual weight on any given day may well be higher, whether it's because you added some load or because you estimated wrong (no four corner actual). If the weight is higher than what you used in the table look-up, then the psi will be insufficient. For that reason, best practice is to go 5 or even 10 psi above the inflation table value, thus assuring you are NEVER underinflated.

Sorry - my chart for my Michelins calls it "recommended" which is far different than an open-ended "minimum." If we're helping newbies, we should be pretty precise in our comments to help them stay safe. I, for one, have often had my misinterpretations and misdirection corrected by the learned members of this forum - thank goodness!

I agree about the weights - if you're MH is not properly loaded to represent your common travel loads when you get your weights, the results will be misleading.

Always load, fill water and fuel, and navigator, etc. then get your weights so that you can look up the manufacturers recommended psi.

[FastEagle]

I always seem to get off on the wrong foot when posting about inflation pressures for motorized RVs.

Because a lot of owners put a lot of credence in what their tire manufacturers have to say about their tire inflation pressures I’m going to provide the reference below from the U.S. Tire Manufacturers Association (USTMA). By reading all the information under the heading; “Determining Proper Inflation Pressure”, on page #43 you may have a better understanding of how the industry explains the acceptable way to set your inflation pressures.

https://www.ustires.org/sites/defaul...TruckTires.pdf

NOTE: Please don't let the document heading fool you when you open it. Page #43 is in chapter #4 and that chapter is exclusively about RV tires, all of them.

[RVPioneer]

That’s a good article and I’ve saved it to documents. Just skimming over it I saw no mention of adding 5-10-15lbs for safety.

I see no safety benefit in inflating tires to 95 when the recommended pressure is 80. That’s nearly 20% above what’s recommended by a team of engineers and lawyers. I’m not smarter than them and I’m not willing to learn that much about tires.

Hitting the exact pressure on the chart could lead to a low reading from cooler temperatures or just sitting for a month. On 30ish psi cars I add 1-2 psi, 70-80psi vehicles add 2-3, 100psi add 3-5. I consider the practice to be annoyance avoidance rather than a safety measure. The above method typically leads to nothing more than regular pressure checks for 3-6 months.