Thanks all - real food for thought there.

I must admit, my experience of tyres in sand has been strange inasmuch as as well as using VSJs and XSs, I also have travelled dunes (Erg Chebbi) with XCLs - aggressive mud pattern - which did not sink! Moreover the Nissan that was with us (lighter, less heavily laden and bigger engine) *did* sink repeatedly on fatter tyres.

Bagnold et al and their experience in the 1930s and 1940s comment that fatter tyres are better and Id agree for the most part, but Roman's point makes interesting comparison. There must be a balance, therefore, for a given weight of vehicle, pressure of tyre and sand density, between fat flotation tyres and narrow resistance-lessening types....

Anyway, acid test, the Defender is going out this weekend to the dunes heavily laden with XZLs on all four paws, so lets see what happens. As a comparison we are taking a second identical CSW 110 on XSs!

Ill report back....

*edit*
Afterthought - Ive seen some of the huge 'serious desert' drilling and mining buggies used by Schlumberger etc out here and they definitely go for the 'fat tyre' route - so much so that one that drove out to sea (dont ask!) actually did *float*. They are the only machines that will drive into the worst parts of the saltmarsh of Qattara and stand a chance of getting out.

Bagnold's experiences from the 1930s started off with Model T Fords on thin thin one and two inch width tyres, so 'fat' is a relative term (Something to tell the girlfriend...!)

[This message has been edited by LandRoverNomad (edited 26 January 2003).]

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