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Discussion Starter · #1 ·
My 646 has the Hi Floatation option on it. I have looked in the 646 owners manual and the tire pressure given is the 27 X 8.50-15. 12 PSI. Would that be correct for the tires on the unit I have?

Thanks,
Ted
 

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Seems to me that you don't have a hoe on the back but you do have some serious counterweights.

Air pressure is there to support the tractor's weight. The carcass of the tire just encloses the compressed air and keeps it in there but in truth, it's the air that the tractor is riding on, not the tire.

There is no pat answer when it comes to an inflation figure. Those are essentially guidelines. Different working conditions can call for different inflation pressures. You need to decide when you have enough air in the tires to support the tractor and also protect the sidewalls of the tire from extreme flexing. You do that by making a judgment call about how big a sidewall bulge you have. If you over-inflate the tire, then the sidewall will try to straighten out and when it does that, it lifts the outer part of the tread away from contact with the paved surface you should be sitting on when doing this.

If you under-inflate the tire, then the sidewall itself will attempt to make contact with the paved surface and you don't want that either. In essence, you want enough air to get the sidewall away from the ground but not so much that the outer part of the tread loses contact because that will reduce your traction. Start with 8 PSI and see how that looks. If you have too much bulge, add 2 pounds to take it to 10 PSI and so forth. If I told you to put 20 PSI in your tires and that caused the edges of the tread to lift, then that would be totally wrong for your circumstances. But if you added a lot of weight to the tractor, then perhaps 20 PSI would be appropriate.
 

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OK....

That doesn't change my answer in any way. Use your eyes and adjust the pressure accordingly. Better to be a tad high than too low. Low pressure causes undue strain on the sidewalls and that shortens the life of the tire.
 

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Discussion Starter · #6 ·
What I was hoping was someone would state "According to the manual" or something similiar and then I would know who got the owner's manual for a Backhoe. I have not been able to locate one. :lol: :lol:

Ted
 

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Ted,

Look in the tech library and you will find an operators manual for a 7020 LBH which is basically the same as what you have. I was wrong on the pressure, the manual says 20 psi but, as Tom, said you can adjust it as needed.
 
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