my bone stock tires that are basically racing slicks are 20x10x9 stock rims on an 2002 400ex i put 22x11x9 and they are to big I can hit like 80mph because of them and they take your lowend power away but 20x11x9 will work better because they will give you a wider foot print and more traction over stock I have no issues with side wall roll even with my overly tall tires. those tires will work fine if you have 9 inch rims.