Tire pressure

[jimrose]

Need some help on tire pressures. Weighed our Motorhome and got reading of front axle 4700 lbs. rear dual axel was 9700 lbs. tires are Michelin LT225/75R16... When I go to the Michilin guide it states maximum load for front is 2680 lbs @80psi and rear is 2470 lbs @ 80 psi. Is this for each tire. It does not clarify and I am sorry if this a stupid question but it makes no sense to me. Any help would be appreciated
Jimrose

[Superchief]

Jimrose, that is the max that each tire can handle safely. Look at this chart:

. Figure out the weight each tire has and then set the tire pressure for each tire based on that. I will calculate in a seperate post and you can see if you get the same result.


Sent from my iPad using Forest River Forums

[Superchief]

The way I figured it was:

Front 4700/2=2350. On the chart it has 2335, so I would move up to the next number 2440, looking up the chart, that say to set each front tire at 70 lbs.

Rear 9700/2=4850. On the chart the number for dual over that amount is 4940, which is the max. It says to set each tire in the rear at 80 lbs.

Hope that helps.

Craig


Sent from my iPad using Forest River Forums

[jimrose]

Superchief. Thanks I got similar results. Any concerns running the rear tires at max or should I have larger tires. These were the ones delivered with the RV
Jimrose

[Superchief]

I would say you are okay. What this tells me, is your rear weight max would be 9882 lbs (4940x2), and you front max weight on those tires is 5360 lbs (2680x2). I would also look at your weight stickers to see what you max weights on your coach should be. Right now you are at 14,400 lbs (4700+9700).


Sent from my iPad using Forest River Forums

[MrJoe]

On ours, we run 75 front and 80 rear. Just like the door jam sticker recommends.

[ATVer]

Max legal gross weight for your coach is 14,500 lbs. You are just under it at 14,400 lbs. Hopefully you weighted it with a full tank of fuel and all passengers on board. You only have 100 lbs left for anything or anybody more without taking some weight out.

[RvBill3]

What does the sticker on the driver's door frame say? That is what the manufacturer recommends. On my Chevy chassis it is 65 psi front and 80 psi rear. Just as important as setting the right pressures is maintaining them. One of the first things I added was a tire pressure monitoring system. Wouldn't leave home without it.


2012 Forest River Sunseeker 2300 Chevy

[Witch Doctor]

I don't have a MH so it might be different, but when I got new mich. for my F250 they said they filled them to the sticker on the door jam.

[jadatis]

Filled your data in my motorhome-tirepressure-calculator wich uses 10% reserve and calculates with an even saver formula then the tire-makers use.
then rear gives even 87 psi as advice , and thats allowed by the tire makers to go 10 psi over your AT-pressure of 80. front 77psi so 80 would not even be that bad.
These pressures give the maximum reserve for things like ,pressure loss in time, unequall loading right left, misreadings of pressure schales etc.
But still comfort and gripp is acceptable.
Here a picture I made of it.


And yes this means that your tires are yust enaugh so an upgrade to F-load for instance or a bigger sise would be wise.
But you dont have to be alarmed , no danger to the tires with these loads .
But see if you can find the GAWR's and GVWR to see if your motorhome is overloaded, thats also not allowed by law.

[Happy Vibe]

Am i missing something? The OP said he has dual rear axle, so would the 9700lbs not be on 4 tires?

[jadatis]

You are right but the lists of Michelin gives it for 2 tires in the dual load line.
Yust what they think is easy how they make the list.
In Europe where I live, these lists are given per axle , so single load gives 2x maximum tireload single and dual gives 4x Dual maximum load ( Dual max load is 0.925 times single maximum load per tire, America uses often 9% reduction so Dual = 0.91 x Singlemaxload. this is to make it easy for the user, but its the same as computer programmes , sometimes this is anoing for the user, my cursur often is in a totally different space somtimes wich is also meant for comfort of the user but mostly only anoying.

[Happy Vibe]

Thanks, should have looked at the chart closer.