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SW Ontario | I have stated it before, so I'll say it again...the AIR is holding the tire up. Stiff sidewalls (firestone) will change this and the rubber will bear weight, the Michelins have a much more flexible sidewall and bear less weight.
I have had this argument time and time with a guy I work with and have gone through great lengths to DEMONSTRATE the principles at work.
Last year we were combining corn in a very wet field and my partner said when the combine is full is will make bigger ruts...right?!? I said no it won't, because the air pressure in the tire does not change and it squats down and spreads the extra weight over a bigger area with the same PRESSURE. He says 'no way, you are full of it etc'...just like you guys are not understanding.
So, undaunted by his sceptisicm, I set out to do a test. I drove over a very wet part of the field emtpy and then stradled those tracks with a full bin. I then brought along the other guy and asked him to pick out the 'full' tracks and the 'empty' tracks. He chose the wrong ones all together, but in reality he guessed, because you could not tell the difference.
The combine was a 9760 with 8 row head, standard 300 bushel bin.
1050/50r32 fronts at 17 psi and 750/??r26 rears at 10 psi.
These tires are magic, you can go through anything using these pressures.
It is very noticable when cutting wheat as you go from a empty bin to a full bin you have to keep raising the header to compensate for the tires squating...which is making a bigger footprint.
The second example (guy still not convinced, says the axle load makes the difference, not pressure) is I have a 6420 with a loader and 16.9/75r28's (i think) and I ran 8 psi in one tire and 25 in the other. Now we only have one variable...right. I put a load on the loader and ran over fall tilled (loose) ground in the RAIN. The tire with 8 psi made just tread marks and did not deflect the soil surface at all, the tire with 25 psi cut in about 4 inches and made a mess. Same weight, same tractor, same everytihing...different results because of pressure.
Just a note, all tires are michelins.
I realize nobody seems to agree with this...that is why I always say bring your tracked tractor to a field and do some side by sides WITH GOOD TIRES. The tracks WILL NOT OUT PERFORM BIG TIRES in terms of compaction IF you run the tires right.
The best thing about tracks is that they are idiot proof, you cant overinflate them etc.
Edited by kinzepower 6/14/2007 11:53
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Tracks vs. Wheels
