I wrote about skirt armour on wheeled vehicles recently, and casually mentioned the effect of CTIS (central tire inflation system) on tires. The system regulates the air pressure inside. At highest setting these tires are very hard and efficient for road travel, while at lowest setting they're really soft, unsuitable for high speeds but best for difficult (especially soft) ground:
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| Sorry for the poor quality, my cheap ancient digital camera had many settings wrong apparently. |
The technology has been introduced many decades ago, the Soviet BTR-152 APC and ZIL-157 light lorry were as far as I know the first examples of quantity production vehicles with CTIS (compare this study). The BTR-152 likely had it in order to achieve similar offroad-performance as halftracks during WW2, at least in Central Europe.
It's exceedingly difficult to find photos of tires with CTIS in very low pressure mode on the internet. That's probably because it looks as if the tires are flat, and it's mostly unsuitable for presentation purposes. Here's an exception, in context from CTIS marketing or farming (where ground compaction due to high nominal ground pressure is a problem):
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| CTIS effect on Unimog |
You can get improved offroad performance without going that extreme, of course. Still, the low pressure mode should be taken into account in regard to
- attempts to shield the tires (changing geometry)
- calculating ground pressure
- actual offroad ground clearance
- probability of sidewall punctures when sidewall touches the ground regularly
- suspension quality offroad (the tire as a "spring" can go a shorter distance, and has a different spring constant = slow driving is advisable)
S O
defence_and_freedom@gmx.de
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P.S.: No comments on this topic because I'm tired of "tracks vs. wheels" debates.
