Conflicted tire size on 2013 tacoma

I plan on getting a 3" suspension lift in the near future ( BS5100's ) I want to buy and install the tires and rims before the lift. I was told by the tire guy that 275/60/18 will fit before I get the lift. The Parts guy at A Toyota dealership says those wont fit. Not even with the lift.... That doesn't seem to make much sense. Can someone with a close set up confirm I can fit that size or bigger?

WTF.......

 

To answer your question for fitment before installing your lift. 265/65/18 is the largest tire size.
http://www.tacomaworld.com/forum/wheels-tires/67550-largest-tacoma-tire-sizes-stock-suspension.html

275/60/18 are not as tall actually, but they are a bit wider.
http://www.tacomaworld.com/forum/tirecalc.php?tires=265-65r18-275-60r18

And Welcome to TW!

 

You will probably be fine but no one can be sure unless you give us wheel specs, offset or backspacing and width of the wheel