By 30" they are referring to the tire size noted on the side wall, not the actual tire height. Rarely is the sidewall size the actual height of the tire.

What the two above me are saying is a 30x9.5x15 tire will fit normally without rubbing, depending on how much your suspension has sagged.

The 31x10.50x15s you are looking at with most likely rub but due to height and possibly due to width as well if you are using stock wheels. Some people claim to fit 31s with no issues, but it's not likely.

To fit 31"s you can go with a 2" budget boost though you may need some aftermarket wheels as well with a different back spacing. After the lift if you use the stock wheels the tires will rub on the front control arms when turning.