In the rain BT090's of all the normal tyres are (IMHO) by far the best, good enough for knee down antics in the rain on track.

If you can either tollerate a 120 tyre on a 3" rim or find a 3.5" (CBR400, RVF400, VFR400 and others) then Maxxis Goldspeed road legal inters are superb in wet/damp/greasy conditions, as good as anything else in the dry and last longer than you might think.

Depending on how much you like burning money, their race wet's, inters and cut slicks are all road legal. Though as they're race compounds I wouldn't like to bet on the lifespan.
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