I think as is we basically have 6s front and 7s rear now so 7s all the way around will be fine. Pretty sure the rears aren't 8s but might be wrong. That +10 is the offset. There are two ways they show offset. The first is actually a worldwide metric standard of where the mounting surface and the wheel center is offset. The other is a traditional terminology of how many inches it sets in from the mounting surface and how many sets out from the mounting surface..ie 4+3, 4+4,5+3...ect I'll see if there is a conversion chart somewhere for this +10