Mt 325-50-15

Ordered them today. 15x12 with a 7 1/2 back space I transfered measurements to the floor with level an framing square. It looks like it should leave about a 1/2 inch to 5/8 on each side of the tire. Summit said they have no problem taking them back if they don't work as long as I don't mount them. I'll get the tires later after I am sure I measured right. Thanks