I agree totally with Tifua. I also crossed the continent coming from West Africa via Tchad Sudan and then down via Rwanda/Congo, and I had a pait of Deserts, front and back. They laste me about 14,000 kilometres, and would have given more, but were starting to get dangerous on tar due to no profile left, i.e. too slippery, but going a bit slower I would have been able to do another 1000 or maybe 2000 kilometres in an emergency. I was riding on an old XT600 '83 model and would never take any other tyre, well worth the extra cost. I also had heavy duty tubes, which is well worth the extra cash as well, also never had a puncture on the rear throughout the life of the tyre, had one or two slow punctures in front, one puncture one valve related problem. I had no tube lock, or whatever they are called in front, I think I would get one for next time. I therefore had soem valve slippages. Important to right this every time you see it, otherwise you will eventually lose the valve. On rear and front, I never fully fasten the valve nuts, I keep them about 1 centimetre off the rim, so that the pump just fits on, this way you can see immediately if the tube is slipping inside the tyre. This works well.
One additional word of advice: I met quite a few germans and others, later in East Africa, with buckled rims etc. who had followed the advice of various "advice" websites etc. which told them to let their tyres down in soft sand to get additional traction. I personally believe that this is total crap and will just soften your tyre, thus reducing life and will get you punctures and possibly buckled rims. I ave done extensive off roading in both cars and bikes and ALWAYS keep my tyres very hard. I never carry a pressure gauge and go according to "thumb rule" by pressing against the side and top of the tyre with my thumb. This has stood me in good stead all the time. If in doubt I rather have too much pressure than too little. I realise that this leads to quite a bit more spinning in soft sand, and thus necessitates air filter cleaning every night, but that is fine. Other downside is that on badly corrugated roads you get a lot of vibration, but rather that than lots of punctures and bucked rims.
Hope this helps, Cheers