They are quite popular over here in NZ. We use the 802 'Cut Offs' and 804 'Turbo Trax' with good results. The 802 would probably be best for bumpy dusty track. I tried the 804's on the weekend, our track was damp all day and they worked brilliantly. I have only used the medium flex and they wear really well. If you get preglued tyres just keep an eye on them as you will usually have to reglue a few areas, other than that a great tyre at a great price!