Berkshire Tire Pressure / Weight Question

[amarzano]

Hello - Newbie with lots of questions..

We had our coach weighed today..

Front Left: 5200 lbs Front Right: 5190 lbs

Rear Left: 5120 lbs Rear Right: 8540 lbs

My first reaction - Holy Crap - someone must have made a mistake.. (Which is a possibility - the RV repair center had this weighed for me - I wasn't there to actually see this..)

Any other owners see such a big difference in the Right Rear? I know this is where the Fridge / Washer / Dryer / Fresh Water tank / etc. sit.. Just wondering if this is normal.. Is this going to cause a problem with handling? (I feel the coach pulls to the right - even after having the alignment checked.)

I did NOT have the family in the coach at the time - but figure that is only about 250 lbs (small kids) or so - and that would be distributed mostly over the front..

The coach comes with Michelin® XRV 255/80R 22.5 (2 in front and 4 in back).

As near as I can tell - I should be at 110lb front and 90 rear? Is this correct? It seems that I am running out of weight margin on the fronts (if I am reading the chart correctly) - Anyone able to validate the correct Tire Presssure I should be running?

I posted this on the Berkshire forum - but think there might be more traffic here..

Thank you,

Alex

[wolfe10]

Alex,

Before we get into the correct tire pressure, with that left right imbalance in the rear, the very first thing I would recommend is having the RIDE HEIGHT checked.

You have two ride height valves on the rear axle. If they are out of adjustment, they can shift a LOT of weight from side to side.

So, before concluding that you have that much imbalance (and setting tire pressure based on the heavier side -- all tires on an axle inflated to the same PSI), verify ride height and then reweigh.

Brett

[amarzano]

Brett -

Thank you for the reply. I had read about the importance of ride height and got the following from Freightliner - which I passed to the alignment shop. I had STRESSED this be checked and correct PRIOR to the alignment.

Front 10" from bottom of Frame Rail to middle of shock bolt

Rear 10.25" from bottom of Frame Rail to middle of shock bolt.

I will be taking the coach back to have them recheck the alignment - as it is still pulling to the right and will AGAIN stress this be checked on BOTH sides of the coach.

Any thoughts on the tire pressure? I'm not sure I am reading the tables correctly.. (not sure if it was clear above - but I am running dual wheels on the backs)

Thank you.

Alex

[wolfe10]

Alex,

Absolutely, reconfirm rear ride height!

Two caveats on tire inflation:

1. All tires on an axle carry the same PSI. The correct PSI is dictated by the heavier wheel position on that axle.

2. The Inflation Chart gives you the MINIMUM PSI for a given weight. Most suggest adding 5 PSI to the minimum as a safety cushion and so you don't have to "air up" after that stop at Walmart, AS LONG AS IT DOES NOT EXCEED MAX RECOMMENDED FOR THE TIRE OR WHEEL.

The Michelin Tire Guide Inflation Chart: http://www.michelinrvtires.com/michelinrv/...tion-tables.jsp Find the weight column that meets you actual weight-- if not an exact match, go "up" to the next column.

255/80R22.5 Michelin XRV

front: heavier wheel position= 5200 pounds. 110 PSI is recommended for and can carry 5205. So that is your correct MINIMUM PSI. Since you are within 5 pounds of maxed out on what those tires can carry, higher PSI is not recommended. But, don't let them get below 110!

Rear: heavier wheel position= 8540 pounds. 95 PSI is recommended for and can carry 8820. So that is the correct MINIMUM PSI. Add 5 PSI safety cushion= 100 PSI.

Now, let's talk alternatives. I never like to see a tire (or any other safety related item) worked to its maximum design specs. Said another way, it is always great to have a safety cushion, particularly with something as important as tires. Our coach runs the same tires, but our front axle only weighs 8,580 pounds loaded vs yours at 10,390 pounds. That is a big difference in how much reserve capacity we have.

SO, I would look carefully at the possibility of upgrading/upsizing/upload ranging the tires. First contact would be owners of the same coach and chassis to determine if any have done this. This will tell you quickly if there is clearance to the fenders/suspension for an upgrade. Another consideration is whether your wheel was designed for the wider/higher load range tire. Dual spacing is a related issue.

Brett

[Guest BillAdams]

Screw the tires, fix the coach!!!!

Sorry, in reality you really have to have a bad reading or the dealer simply wrote the information down incorrectly. If you can't do anything else, go to a local truck stop and use their scale. You may not be able to do anything more than weigh the front and rear, but I suspect you will find that the front comes in around 10,400 and the rear comes in around 10,400 (or 16,700) and not 13,100. This would at least help clear your mind about any major chassis issues. Then, find a good company, such as RVSEF, to do a good 4-point weighing and proceed with good information from there.

Do you know the rated capacities of your axle/tire combination? It even sounds strange that a coach would weigh the same on the front axle as the rear. If this were true, why would you need four tires back there? Maybe in reality it's the left rear number that is too low and it should be 8,120. That would actually make much more sense.

[wolfe10]

Bill,

Agree, the rear axle readings are just (ever so slightly) short of unbelievable.

BUT, it is the front axle that is right at the load capacity of the tires. That is the reason for my recommending considering upgrading the tires, not the "unusual" rear wheel position readings.

Brett

[Guest BillAdams]

You are correct that if you get the right readings on all 4 corners the math will likely add up to a coach that just barely squeaks by on the tire capacities, both front and rear if I am right that it will be over 16,000#s. That's why I asked about axle capacity. You can put bigger tires but if your axle is not capable you are still in big trouble.

If this coach is fully loaded for travel but you still need to add passengers you are still treading on thin ice. If this coach is new (new to you) and mostly empty then you are in really big trouble as you will not be able to add much more than a roll of toilet paper before you are overloaded.

[amarzano]

Here is what I am learning...

I paid to have the RV weighed - and can't trust the numbers.

I paid to have it Align and the Ride height checked and it still pulls right and can't trust the ride height.

I need to stop paying and start finding some quality folks to do the work. Sorry - just whining.

Can anyone suggest an alignment in the San Francisco Bay Area that can give a quality result?

I have been trying to find a scale - but with no luck yet. (I want to find someplace that can again measure each wheel.)

[wolfe10]

Give a call to your local Police/Highway Patrol. Talk with the truck weight enforcement division. They generally use the portable scales that do weigh each wheel position. See if you can arrange to meet them at the beginning or end of their shift and have them weight your coach.

And, you can measure ride height. Park on a flat area. With coach running (air suspension up), measure ride height -- it sounds like you have the ride height specs. I would NOT recommend you adjusting it without jack/safety stands and knowledge of how the valves work. BE SAFE OUT THERE.

Brett

[amarzano]

A quick update..

Spoke to Forest River today. They politely told me the above numbers could not be correct.

I should be looking at about 8500lbs per side on.the rear and 4500lbs per side on the front.

I will try to get the coach weighed this weekend. I should be able to at least get accurate

Axel weights and then zero in on the correct pressure.

[wolfe10]

Did you try to contact the truck enforcement division of your local/state police department to see if they would do the individual wheel weights for you?

Brett

[amarzano]

Brett -

I have been trying to get thru to the Highway Patrol (CHPs) but without luck at this point.

Forest River followed up and provided the following numbers:

FR - 4614 FL - 4586

RR - 8458 RL - 8362

This is for MY coach as it was when it left the factory. Apparently - they weigh each unit as it leaves. I thought this was pretty interesting..

Did you try to contact the truck enforcement division of your local/state police department to see if they would do the individual wheel weights for you?

Brett

[Guest BillAdams]

That's great information to have, but it just re-enforces the fact that you need to get some accurate information. Get the coach weighed before you put too many miles on the coach to ensure that everything is in order and make the necessary air pressure adjustments. I recommend that you do this once a year if you are just starting out as you will be adding and subtracting things on a regular basis. After a few years you can get weighed every couple of years just to ensure things are still OK.

[amarzano]

Thank you all again for the advice.

I had the coach weighed at a CAT scale before our trip. This is close to

Loaded, minus a DW and kid.

Front: 10,020lbs

Rear: 17,280lbs

The original weights I posted were obviously wrong. I still have not been able

To have each wheel weighed, and will keep trying.

I will also weigh the coach on the way back from the weekend - with everyone on board and post that tomorrow..

[Guest BillAdams]

Thank you all again for the advice.

I had the coach weighed at a CAT scale before our trip. This is close to

Loaded, minus a DW and kid.

Front: 10,020lbs

Rear: 17,280lbs

The original weights I posted were obviously wrong. I still have not been able

To have each wheel weighed, and will keep trying.

I will also weigh the coach on the way back from the weekend - with everyone on board and post that tomorrow..

With the max front tire carrying capacity at 10,410 at full inflation you are very close to the tires maximum capacity. You might want to find out if the axle is rated for a higher capacity and consider installing new tires that will more safely carry the load.

[amarzano]

With the max front tire carrying capacity at 10,410 at full inflation you are very close to the tires maximum capacity. You might want to find out if the axle is rated for a higher capacity and consider installing new tires that will more safely carry the load.

Fully Loaded and ready for the trip we are at:

10,160 lbs Front

17,520 lbs Rear

I will see if I can find something in the Chassis Manual about loads for the front Axel.

Alex