Where would I find some tougher tires and tubes for MB? Looked at Wal Mart etc. but they only seem to have tubes filled with Slime. I'm looking for More puncture proof. Have 6 year old stockers and used to get flats from stickers even. (Weeds here.) Was told of tube inserts like hard foam that replace regular air filled tubes? Would like flat proof tires for longer rides. 26"x125 mountain bike.