Here you go:
www1.istockphoto.com/file_thumbview_approve/382537/2/istockphoto_382537_muddy_tracks.jpg
www.digger.ch/images/products/d-2/tracks/Tracks_adaptive_Digger_D-2.jpg
http://history.amedd.army.mil/booksdocs/wwii/actvsurgconvoli/Figures/fig44.jpg
http://milov.nl/files/020607_tank.jpg
www.forceforgood.co.uk/junk/tank4.jpg
www.vac-acc.gc.ca/content/history/secondwar/netherlands/images/pa_42597_neth.jpg
www.army.mod.uk/atra/the_armour_centre/images.htm
http://www.uniteddefense.com/i/prod/ags_mud_Web_100.jpg
http://www.qohmuseum.org.uk/sherman_1.jpg
http://www.25thida.com/TLN/v545_10.jpg
http://www.mayoff.com/perths3.jpg
http://www.tanks-alot.co.uk/SpecialEvents.htm