Not sure if you're saying I'm just making things up - here are some of the first links off a quick google: - http://www.fwi.co.uk/machinery/tractor-tyres-make-

Not sure if you're saying I'm just making things up - here are some of the first links off a quick google: - http://www.fwi.co.uk/machinery/tractor-tyres-make-sure-your-pressures-are-right.htm http://www.fwi.co.uk/machinery/tractor-tyres-make-sure-your-... - https://www.agribrink.com/ https://www.agribrink.com/ - http://www.omafra.gov.on.ca/english/crops/field/news/croptalk/2013/ct-1113a1.htm http://www.omafra.gov.on.ca/english/crops/field/news/croptal... Now I'm not a soil scientist, but I am a programmer who's for the last year or so been programming models for assessing soil threat risks, including soil compaction (one of the biggest soil threats in agriculture); and work with some of the world's foremost expert scientists in this field, as well as with representatives of e.g. machine manufacturers. They all say that compaction is mostly due to increases in weight of machinery, and that proper tire pressure is the most important mitigation measure we have available. Liquid-filled tires are never mentioned in this context, it's a rarity. You claim that 'most' tractors run liquid filled tires - I'm not sure what you're basing that on, or what locality you're talking about, but while I do not have any numbers at hand, I have never heard of this being something other than an incidental thing. For example, the Michelin site (http://agricultural.michelinman.com/us/Properly-use-your-tires/Ballasting-tyres-for-better-use http://agricultural.michelinman.com/us/Properly-use-your-tir...) mentions it as a possibility, but not as something that 'most' tractors would have.