275/50/15 on a 7" wheel ?

Unfortunately you will not make good use of the wider low profile tire,it will be strecthed over the rim and pull the outer edges down and you will have a high spot in the middle.No matter how much you air them down the minute you hit the gas they will gow and you will be back to having all your traction in the middle part of the tire.If you are sticking to a seven inch rim go with a taller tire like a 275/60/15,or better still a slightly narrower/taller like a 255/60/15,the extra sidewall will give you a wider footprint on the narrower rim.Alot of racers use only a 30x9.5x15 slick on sub 10 second cars since a taller tire/more sidewall will always give you a bigger footprint when comparing identical tread widths.