imo 18 is just too short for the dunes. You will end up dragging your chain and rotor through the crap too much or the skid plate if you run one. I also feel the 8" wide is to narrow vs the flowtation advantage of 11 wide. This is a very hard topic to get YOUR answer. Most riders have a different forward bite preferance and true need. You can get over hooked real easy and I myself prefer less hooked up then most for duning fun. Swingarm length is a big factor in picking the right tire for your needs. I would tweak my tire selection if I was switching between a stk 86 87 and a stock 88 89 let alone a +? extended swinger.