I don't know much about wheels and tires so I'm posting this question. Somebody is selling me 4 set of tires size 205/50 x 16 mounted on wheels 7" in diameter with 4 lugs. The specs in my civic honda lx 1998 is only for 14". Can I use this upgraded tires and wheels? Will it significantly reduce my mpg? Any input will be aprreciated. Thanks. Lester