I've been wanting to get some nice AT's for my 87 4runner since it sees 95% road and my Michelin MT's are dryrotted and very noisy.   I'd like to get brand new, but considering you can easily spend $600+ on tires I thought about searching for some nice takeoffs with good tires from a new Toyota to save money and to keep the stock look.  In doing so, I've found some 05 and up Tacoma alloys for a good price, but am concerned about the backspacing (see example picture below).  I've searched and searched, but haven't found the true number for these wheels.  My best source doesn't seem very reliable and says 5-5.25".  I don't want to run wheels spacers, so i'm hoping its like the 3rd gen 4runner alloys at 4.75".  My current wheels are steel procomp's 15x8 with 4.5" backspacing i think and my 31's only stick out slightly. 

from what to what?  I know that 4.75" minus 4.5" is 1/4", yes.