there are several different answers depending on how much rubbing you are okay with. TECHNICALLY speaking a 215/70R15 (27") tire WILL fit in stock form, but it will rub when you bottom out or in hard turns with bumps. With our 2" inch lift we have yet to get any rubbing under any circumstances with a 215/70R15. If you wanted to get rid of the rubbing in the stock form you should shoot for an overall diameter of 26". Speaking from experience, 27.4" is the absolute maximum you can run (regardless of how big of a lift you run, without the tire rubbing on the bottom coil mount of the front struts. 27.6" will just barely rub. Keep in mind if you plan on going through mud, running snow chains, or even small rocks getting caught in the tread you will want some clearance.