Tires off ground question

[AikenRacer]

Every now and then when I level the mh, a tire will end up being off the ground. Keep in mind, this is a tag axle. This has never bothered me until I started seeing others spend a lot of time driving onto wood just to keep tires from being air borne. Just read an article in the new Motorhome magazine page 64 and it says "If any of the tread is unsupported, it can cause internal damage that may not be obvious at the time." At my job I see huge cranes all the time, set up for days, with all their tires off the ground. In fact this is the proper protocol for cranes. So where's the problem? Someone please inform me. If I have to carry lumber with me for this it will greatly add to the aggrivation and time in setting up....but I don't want to tear up my tires. Comments??

[wny_pat1]

Like I said I was reserving judgement until I read the article (Motorhome Magazine, October 2013, page 64 - "LEVELING") the OP was talking about. Will I have, and most of you have the OP's post all wrong. And I think he completely misunderstood the information concerning this type of leveling, and should go back and read it. The article is not about tires being unsupported off the ground. It is about a tire being on a block or board for purposes of leveling. And yes, the complete contact patch of the tire has to be on the board. The contact patch of a tire is the portion of the tire that completely touches the pavement or leveling board.) If any of the portion contact patch of the tire is hanging over the edge of the board, it can cause internal damage to the plies of tire. The whole purpose of the that portion of the article was to tell you to keep the contact patch of the tire completely on the block or board that your are using to level your rig!!! It is not about tires hanging from the suspension.

[Lobstah]

JimM68 wrote:
I love these discussions....

I am of the opinion that the motorhome's jacks are in fact designed to hold it's weight. (I've seen some with tiny cylinders that I wouldn't trust to lift a prius... My powergear 3" cylinders will lift a lot.)

I am further of the opinion that a big box on sticks is not ever rolling anywhere.

I also kbow that the air suspension on my coach does not mind beinig completely onloaded, and holding up the tires, wheels, and axles.

While I prefer to leave all four wheels on the ground, and I try to pick a site / location that will let me do this, or just lift one or both fronts off the ground, I do not fear lifting one or both rears off the ground. A box on stilts is not rolling anywhere.

I do understand others might have different opinions. When I back my rig into my driveway (rear down 1 foot from the front, left to right also off 6") and level it, and it actually "rolls" backwards into the pool, you can all laugh and tell me "I told you so"

X2...I couldn't agree more. Someone needs to explain the physics to me that allows a 25-40klb box siting on 4 pads to move anywhere. Each one of those pads has between 7k to 10k of weight on it. Try putting a 5 ton block on top of a 12" pad and drag it somewhere.
Not going to happen.
Now...if you're on a 20% grade? Sure...haven't seen that in a campground yet.

Jim

[JohnnyT]

I have never thought that having a tire suspended was hard on the tire(s) that were suspended... I would never want to have the rear tires suspended since the rear tires are the source of the emergency breaking to prevent any motion. Even though jacks are down I would not want to subject the jacks to lateral stress by having the rear wheels off the ground where any slope was involved.

The only concern I have ever pondered was the stress on the suspension components of prolonged absence of ground contact.

I do think that if there is a circumstance where a tire is bearing weight for an extended period of time with only partial tread contact that could be damaging so I just avoid that scenario.

Having tires off the ground is less likely on a diesel pusher since part of the leveling process is to deflate the air suspension so the house starts out much lower than a non air suspension motorhome.

I can not conjure up the logic that would prescribe damage to a tire that is suspended and not weight bearing...

JohnnyT

[Canadian_Rainbi]

bob_nestor wrote:
Hmmmm, what about the tires on airplanes or the ones used on the space shuttle? Being off the ground doesn't seem to be a big concern with them.

Yeah, but those tires are just a tad more expensive and at a guess a little better engineered.

[Devonm2012]

As I was walking the RV park we are currently in this morning, I noticed a 40+ foot tag axle high end Fleetwood that had the front end raised WAY up off the ground and BOTH front tires were missing! Not sure what was going on, but there was NOTHING supporting the front of the RV other than those jacks.

[JimM68]

I love these discussions....

I am of the opinion that the motorhome's jacks are in fact designed to hold it's weight. (I've seen some with tiny cylinders that I wouldn't trust to lift a prius... My powergear 3" cylinders will lift a lot.)

I am further of the opinion that a big box on sticks is not ever rolling anywhere.

I also kbow that the air suspension on my coach does not mind beinig completely onloaded, and holding up the tires, wheels, and axles.

While I prefer to leave all four wheels on the ground, and I try to pick a site / location that will let me do this, or just lift one or both fronts off the ground, I do not fear lifting one or both rears off the ground. A box on stilts is not rolling anywhere.

I do understand others might have different opinions. When I back my rig into my driveway (rear down 1 foot from the front, left to right also off 6") and level it, and it actually "rolls" backwards into the pool, you can all laugh and tell me "I told you so"

[wny_pat1]

AikenRacer wrote:
Just read an article in the new Motorhome magazine page 64 and it says "If any of the tread is unsupported, it can cause internal damage that may not be obvious at the time." At my job I see huge cranes all the time, set up for days, with all their tires off the ground.

I think taking the sentence out of context in the paragraph, a lot is getting left to the imagination. I have to reserve judgement til after I read the article. I am thinking that he meant to say, if any of the thread is supported and some of it is not, there can be internal damage to the tire. Don't think the author is saying that there can be damage if the whole tire thread is unsupported, but only if part is supported and part isn't supported. The whole footprint of the tire has to be in contact with the block or support.

[fourmat]

dont like both front off the ground but 1 front i have done several times I never leave rear up. As far as tires being damaged being off the ground what about people that carry a spare? sounds kind of stupid

[wa8yxm]

timmac wrote:
That article has to be wrong, sometimes I just don't know who writes these things, what about all the times cars are on lifts for repairs, what about spare tires, etc, etc, sounds crazy to me..

Tires are not in the least damaged by being off the ground... At least not the tire that is off the ground.

What they are refering to is this: IF you level, as I do, using blocks, then all tires need to be supported or the tire on the blocks will be carrying double it's load and that can cause damage.

I have also read about folks who claim that if you lift a tire off the ground it will somehow damage the suspension.

Suspension designed to hold up thousands of pounds of motor home is going to be damaged by holding up a couiple hundred pounds of tire rim and axle/brake... I don't think so.

The major danger (And this DOES not apply to tag axles at all) is this... If you lift all your front or rear wheels off the ground the rig can move sideways, Or if you lift just one rear wheel forward and backward, And jacks are about a kilobuck a pop installed.

Now.. as for the "Share the load" If you are leveling with jacks, then when the tag comes off the ground the remaining wheels are carrying very little load.. The jacks hold the rest.

[dieharder]

Never had this situation, but if I did, I would use blocks under the tires. I use the jacks to keep the rig steady and not support the entire weight. Although they may be able to fully support the weight, I'm not sure they were designed to for long periods of time. To me the blocks are cheap insurance.

[MarcW]

My air leveling system very seldom lifts a tire off the ground.. 🙂

[MustangGT]

We had to lift the front wheels off the ground (about 4") for the first time to level our RV last weekend.
Afterwords, I remembered people cautioning that air-bags were not designed to support the weight of the front suspension, so I took a look and the bags were STRETCHED! So we immediately adjusted the jacks and repositioned some 2x12 boards under the front tires to take the weight off the suspension.
the people next to us had to do the same, but their bottom RV step was at about 24" off the ground! their RV looked like a 30 footer. They used a little step stool to make-up the distance.
Looking around the campground, most had supports under their fronts, but several just let the tires hang. Wouldn't be a tire problem with no bags, but some were DP's and I thought all DPs had bags.

[rgatijnet1]

I keep the frame level as I am using my leveling jacks. This prevents any undo strain on the frame, windows, windshield, slides, etc. Once level, I make sure that my rear tires are not off the ground and do not worry about my front tires.
My front and rear leveling jacks stabilize the coach since they are firmly attached to the frame. Putting blocks under my front or rear tires is not going to stabilize anything because of the spring suspension.
If having a tire suspended off the ground is going to cause a problem with the tread, then my spare tire is in trouble. :B

[tony_lee]

There is always some truth in some of these commandments but they often get exaggerated and enshrined in law for no good reason. Something that will damage a tyre if carried out at 65mph isn't necessarily going to do any damage at all if carried out at 1mph. Conversely if hitting a fist-sized rock on a back road at 30mph doesn't seem to do any harm to a tyre, why should running up slowly onto a flat block of wood 2" narrower than the tyre do any harm.

Same with lifting front tyres off the ground - no big deal. Nothing will be strained by having to support the weight of the axle while stationary - simply because it is designed to hold it at full downward extension while moving.

Lifting both back wheels off the ground is obviously more problematic because then you are relying on the jacks to be the brakes and some of them won't stand up to a lot of sideways force. However many think that as long as the tyres are on the ground they are OK but once any weight is taken off the wheels, the braking capability is reduced and if the tyres are completely unloaded the braking is zero even though the tyres are still touching.