Tire inflation question

[RoyJackson]

See above color hilited from your link.
larry

Looks like I should have read my own link more thoroughly!

Anyway, read this:

In general, contact pressure largely determines the potential for compaction in the plow layer, while total axle load determines the potential for subsoil compaction. This is important when comparing tracks and tires for compaction effects and depth.
Tracks exert a ground pressure of approximately 5-8 psi depending on track width, length, and tractor weight. Radial tires exert a pressure of 1-2 pounds higher than their inflation pressure. For example, if a radial tire is inflated to 6 psi, the tire exerts a pressure of 7-8 psi on the soil. However, bias tires inflated to only 6-8 psi cannot operate efficiently and easily wear-out with such low tire pressures, consequently they have to be inflated to 20-25 psi.
Research has shown that tractors equipped with either tracks or radial tires create compaction in the top 5-8 inches, however, compaction effects were negligible below that depth. But what effect do tracks have on subsurface compaction when used in conjunction with heavy field equipment, such as grain carts or combines? Keep in mind that depth of compaction is a result of total axle weight and the role of ground contact pressure is secondary. Whether the equipment uses tracks or tires, the total axle load is nearly the same. Tracks will improve traction and ride-ability, but a 25-ton per axle grain cart will still create subsurface compaction.

(the above is from Soil Compaction: Causes, Effects, and Control)

It appears that both arguments are correct depending upon which type and component of soil compaction is being discussed...

Jeez! Being a farmer is more complex then I ever imagined! What I'm getting out of this is a farmer is best off using radial tires or tracks to reduce soil compaction...radial tires in order to reduce required tire pressures (contact pressure), tracks to reduce both contact pressure and the effect of total axle weight.
Pretty interesting...

 

[SPYDERLK]

That 20-25 bias tire psi is bogus. The spread between 6psi for radial and 20psi is a cherry pick. There is a spread tho. You just dont find big bias AGs needing more than the mid teens at their rated load or even a bit above. And youre not going to find an equal sized radial supporting that same load optimally at 6psi.
larry

 

[RoyJackson]

That 20-25 bias tire psi is bogus. The spread between 6psi for radial and 20psi is a cherry pick. There is a spread tho. You just dont find big bias AGs needing more than the mid teens at their rated load or even a bit above. And youre not going to find an equal sized radial supporting that same load optimally at 6psi.
larry

Well, I'm not a farmer, nor an agricultural expert...these folks are the "experts" and very likely more knowledgable then you or I on the subject.
As far as the so-called "cherry pick", I'm sure they worked to the extremes of the types of tires for validating their studies and knowing that tires/weights and loads in the middle can be extrapolated from the data they provide.
This particular study was the only one I found that discussed both types of soil compaction. However, there is a lot more information on this subject then I ever imagined so I'm sure I didn't cover the entire spectrum of information.

Out of curiousity, how do you justify "You just dont find big bias AGs needing more than the mid teens at their rated load or even a bit above. And youre not going to find an equal sized radial supporting that same load optimally at 6psi."? Is that your opinion based upon subjective data (your experience)?

 

[SPYDERLK]

Out of curiousity, how do you justify "You just dont find big bias AGs needing more than the mid teens at their rated load or even a bit above. And youre not going to find an equal sized radial supporting that same load optimally at 6psi."? Is that your opinion based upon subjective data (your experience)?

You can look at how the loaded tire sits and use your head. Or you can look at sidewall ratings. Max pressures for field AGs is under 20, and typically those higher pressures are for max speed use [20mph]. In practice most are run in the 12 to 16 range on field. HD AGs [10ply] are for higher loads and can be inflated higher.
larry

 

[RoyJackson]

You can look at how the loaded tire sits and use your head. Or you can look at sidewall ratings. Max pressures for field AGs is under 20, and typically those higher pressures are for max speed use [20mph]. In practice most are run in the 12 to 16 range on field. HD AGs [10ply] are for higher loads and can be inflated higher.
larry

Then you're using "seat of the pants" data rather then scientific...basically, your opinion.
OK...just curious...I was surprised you used posted

That 20-25 bias tire psi is bogus. The spread between 6psi for radial and 20psi is a cherry pick. There is a spread tho. You just dont find big bias AGs needing more than the mid teens at their rated load or even a bit above. And youre not going to find an equal sized radial supporting that same load optimally at 6psi.

since you didn't qualify it as opinion... That's cool though...