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Trabuco

Tire Pressure Before Having Motorhome Weighed

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I'm new to the motorhome market, just purchased a new-to-me 2005 Monaco Diplomat and have a question on tire pressure. I have Goodyear G670 275/70R 22.5. The maximum pressure on the tire is listed at 125psi. Inside the coach next to the divers seat is a label indicating cold tire pressure of 115 psi for the front and 95 psi for the rear. Realizing I need to get all four corners weighed, is the 115/95 psi a reasonable pressure to go with until I can get my motorhome weighed?

One more question: Does anyone know where I can get the four individual corners weighed in Southern California?

Thanks.

Ken

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Ken,

Welcome to the FMCA Forum.

The PSI on your GVWR sticker ASSUMES each axle is loaded to its GAWR. You can get full axle weights at most all truck stops. That will tell you if you are in the ball park.

You are absolutely correct about needing all wheel position weights, as ASSUMING perfect left/right weight distribution is not reasonable.

Would also suggest having RIDE HEIGHT checked/adjusted before final weighing . It is a good thing to check annually. And if off even an inch or two, can transfer a LOT of weight (Just think how many of your really strong friends it would take to lift that left rear corner two inches)! Yet, seeing a two inch out of spec on a 40' coach may be very difficult.

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Your coach will have three RIDE HEIGHT VALVES. They determine how much air (height) is in the air bags. Two on one axle (usually the rear) and on the other axle.

The rod that connects the axle to the ride height valve is fairly light-- you could bend it with your little finger. So, checking is reasonable as running over a piece of tire on the road can easily bend the rods.

Ride height affects ride, handling and suspension component wear. If the rear is too far out, you can take out drive line components-- 2" doesn't seem like much, but with that very short drive shaft on a DP, it dramatically affects drive line angles.

And, as mentioned in my post above, it can shift a LOT of weight from side to side. And on tag axle coaches, adjusting the tag can make a HUGE impact. At a recent Cat RV Club Rally we individual wheel position weighed all coaches. Ended up making major adjustment (we are talking about thousands of pounds) on all but one tag axle coach.

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Just when I thought I was up on everything someone throws something new in!! Never to old to learn! Is this something I could tackle myself or is this strictly a shop kind of project?

I appreciate the info Brett.

Ken

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Ken,

Can't answer that. Depends on your mechanical skill. Not that tough.

But, you do need safety stands to make sure the coach doesn't come down on you!

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I stopped at a truck scale that was closed, had the Co pilot go move the cones out of the way, then drove only the rt side onto the scale, one axle at a time. Combine that with weighing the whole axle, and you have all 4 corners. Nice they leave the scales turned on so you can do that.

Yes, she put the cones back before we left.

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Guest BillAdams

That's a very cool thing in OR. When the weigh stations are closed for truckers they are open for the rest of us. It's a great starting point and a nice way to confirm that things have not gone South since you last 4 corner weighing, but a 4 corner weighing needs to be in your plans.

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Ken,

I believe Redlands Truck & RV has the scales. 888-249-0124

Henderson RV & Redlands should be at Quartzsite, AZ in Jan with their scales.

When CHP sets up the temorary truck check spots, & they are not busy, they may weight all corners for you.

The CHP truck station in Castaic may also weight you, if not busy, but not all 4 corners.

Harry Salit

97 Discovery

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Ultratraveler,

Welcome to the FMCA Forum.

Your chassis manufacturer has your ride height specs. You will likely measure from some given point on the axle to some given point on the chassis.

So, armed with those points and a ruler/tape you are good to go.

Be sure to use safety stands if you have an air suspension.

Brett

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Ken,

From your home in Trabuco Canyon, there is a good weigh station nearby in Tustin. Schlick Moving & Storage, 2721 Michelle Drive, Tustin. It's roomy, never crowded, and you'll have lots of time to weigh each side, front and back, and so forth. Their phone number is 714-731-5500.

Good luck and happy travels.

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Ken,

Is adjusting the ride height a simple task that I could do myself? Or, should I let the Pros do it?

I'm in the Conroe, TX area, anyplace close to me that can perform this task?

My reason for asking is;

I noticed irregular wear on the inside front driver side tire. I'm going to get the alignment checked and thought I should get the ride height checked too. If the ride height is off could it affect tire wear?

I'm very good at keeping up on tire pressure so don't think that was ever a contributor.

Thanks for any feedback,

John

2008 Fleetwood Bounder Diesel 38F

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Yes, always check ride height BEFORE doing an alignment. Though ride height on an air suspension DP will not cause uneven tire wear, it can sure affect a lot of other things like ride, handling and wear of suspension and driveline components.

And there is nothing difficult about checking ride height. You DO need jack stands/safety stands to support the weight of the coach anytime you go under to work, particularly if adjusting the ride height. Get the ride height specs for your chassis from your chassis maker.

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