Thanks to this group I have identified my mini-bike to be a WREN. Questions. What are the correct tires to put on it size wise? Currently has a 40/3.00-5 ribbed on the front. and a 4.10/3.50-5 knobby on rear. Looks like if the rear was not worn down so much that it would not clear the brake pad. Also the gas tank on my BS engine has the bottom pounded in for tire clearance. Do they make a smaller tank for this engine? Thanks for the help. Jim