Everyone racing 17" minis uses GP125/Moto 3 slicks. bridgestone, Dunlop, sava/mitas and PMT all make a set. the fronts are generally 90/80-R17 the rears are generally 115/75-R17. You should use tire warmers unless its a pretty hot day, but they aren't absolutely essential. people jam them on 1.4" rims all the time. The profile isn't optimal but it's fine. You could also just lace up the correct 1.6" excel
were I you, I'd be designing my frame around running 12's and using the Sava mc36 120 width or the PMT slicks. the 12's are well known for being the best for kart tracks. It's pretty noticeable how much quicker you can throw the bike around and the width and profile makes it feel impossible to low side.
https://www.73motoparts.com/product-page/honda-crf150r-rb-mag-wheels-set (edited)