Axle and Frame Height Question for Changing a Tire

[tld]

Okay, I know the whole tire changing and where to place your jack issue has been beat to death. That, however, is not my question or issue. Some say okay to place jack on axle as long as you get it as close to the tire as possible. Axle and frame manufacturer say to always put jack on frame. Okay, I do get all of that.

So, I'm trying to prepare for all flat tire situations, but here is my challenge. My frame to ground distance is pretty large at 27 inches (16" tires properly inflated and frame has been lifted to the bottom hole adjustment). The bottom of my shackle U-bolts to ground distance is 13 inches. Again, this is the distance with properly inflated 16" tires. So, I want to have the right type of bottle jack(s) so that, in an emergency, I can either jack from the axle or the frame.

First question then: if I have 13 inches to the bottom of the U-bolts when measured with an inflated tire, can anyone tell me what the approximated distance will be with a flat tire? In other words, to get under the U-bolts, what will be the min. height of bottle jack need to be with a flat tire?

Second question: Since I have a frame to ground distance of 27" with the fiver setting normally on properly inflated tires, can anyone give me an approximated distance from ground to frame that I would need to jack the frame to get a fully inflated tire on? Since most bottle jack only have a max. height of about 16" to 17", I'm a little nervous about the stability of having to stack the jack on 10" or more of leveling blocks or wood blocks!

And, I do have a homemade drive on platform that works just like a Trailer Aid. And I have tried it to see if it will work and it does barely bring the inflated tire off the ground. But, I'm a little nervous to use it because of reading reports that using this type of method can cause a shackle Link on a MOR/ryde type of system to flip and apparently that can create some difficult problems.

Sorry this is so long but thanks in advance for any insight on this issue.

[Mopar_Earl]

You're making it harder than it needs to be. Get yourself a large bottle jack rated more than you need. Use a block of wood under it or Lego blocks to get the height you need.

Never jack on a trailer axle. Always the frame. I use my auto leveling jacks to left the tires off the ground when needed. Haven't needed to use my bottle jack yet. But it's always in the basement along with a HD 4-way lug wrench, safety triangles and torque wrench. I keep crap loads of Lego blocks and a few pieces of 6X6 wood blocks.



Earl

[Cdash]

I would think you could come close by measuring up from the ground to the rim on your rig and figuring that dimension in your numbers.

It is interesting that people are afraid of jacking from the axle, but have no issues driving up on a ramp that puts all the camper load from that side on ONE wheel, likely exceeding the axle load rating. I'd be more concerned of bending an axle or causing some other problem that way. To each their own.

Also, I don't like lifting from the frame, especially due to the height of our frames. I put a jack (usually my F-350 stock jack) under the axle between the spring U-bolts (right where the spring loads the axle without bending it). The truck jack has always fit under the flat tire and has been able to lift high enough.

[tld]

Cdash, measuring from ground to rim would probably get me pretty close. So, just to be clear, your putting the jack's lifting saddle directly on the axle between the spring u-bolts?

[goducks]

Get a 5 ton bottle jack at Harbor Freight or somewhere cheap. Stick it under the axle at the location where the U bolts are. You only need to jack the axle up about 1.5" for the tire to come off the ground. No different than driving over a big driveway bump. Trying to jack the frame up on one side is asking a lot for no big gain. You'll have to raise the frame up 4-5"+ because the frame will raise up before the springs reach their low hang max and at that point the tire finally comes off the ground.
I've jack my trailers up many time by just placing a jack under the axle between the U bolts and have never had an issues.
When you hit a bump the axle is pushing up in the same place that a bottle jack would when placed near the U bolts.

MFG's are just doing the CYA thing because no doubt someone will place the jack too far under the trailer and cause damage to the axle and possibly themselves.

[Cdash]

Originally Posted by tld

Cdash, measuring from ground to rim would probably get me pretty close. So, just to be clear, your putting the jack's lifting saddle directly on the axle between the spring u-bolts?

Exactly!

There have been occasions when something (like the flap of a flat tire) prevented me from getting it there, then I placed just inboard of the inboard U-bolt. As the guy before me stated, you are lifting the axle and not the entire trailer. The axle isn't made of tin foil! The key is to keep it as close to the spring location as practical without getting overly obsessed with it. You could go several inches in from the spring and not have problems, but your best to keep the load path in a straight line when possible.

[TxLoser]

I had discount tire mount my last set of tires. Placed the jack right under the U-Bolt and lifted only a couple inches. I too don't see they're being any more stress on the axles doing it this way than driving up on leveling blocks. Should I get a flat, I'll use my truck's bottle jack and some Lego blocks.

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[3'senough]

Having done this several times for maintenance here is what works for me.

6x6 and 4x6 with a 10 ton bottle jack. On soft ground I lay a 2 x 12 to get a stable foot print. It takes about 7-8 inches of travel to get the tires loose from the ground using the frame jack point.

Do not jack the axles as you could crush or bend them.

I carry the block wood anyway for the stabilizers and the jack is always with me in my TV for both trailer and TV.

The legos will most likely crush/crack under the pressure of the trailers weight being up in the air and I do not recommend that as an option.

[goducks]

If your axles crush from putting a bottle jack under the spring perch then you have major concerns. I would bet that you've never tried putting a bottle jack under the spring perch and lifting the tire 1.5" to even check your brakes for adjustment.
Each to his own I guess.

[Mopar_Earl]

Trailer axle tubes are hollow and thin wall. While the whole tube is strong to it's rating, putting concentrated weight in one spot can crush it, bend or distort it. That's why they say not to. Your axle, your choice though.
Any RV shop I was around or worked in, always jacked them at the frame. Large floor jack with a 6X6 block on the saddle. One RV shop I worked in had a nice air jack that went high enough without a block of wood. Ahh, I don't miss my RV shop days. Lol


Earl