Hey guys ... I always watch how many miles I get out of a tank of gas .. just habbit I guess .. but I have noticed in the last couple months my milage has gone down.... All I have done in that time is go from stock 13's to my 17's and replaced the spark plugs.... before I would get aprox 320-350 out of a tank of gas. now I get 260-290, could the heavier wheels make that much of a diffrence ? or should i be checking for a more serious problem ? thanks

NS