[Chevelle-List] Rear Tire Size

[Lojac]

What is the largest tire size that will fit under stock wheel wells on a 69 Chevelle?  Right now I am running 235/60r14.  I would like to go to a 17 in wheel since I am planning on putting 3.73 rear end gears.  This will lower my RPM's on the highway by about 600+ RPM's if I can go with 275/70R17 tires.  Is there a website on this (tire sizing, not RPM calculators)?  I know that I am asking a lot of questions tonight.  Just point me in the direction of the nearest website if I ask too many.