i just bought an 88' buick reatta...the rim size right nowis 15 but i was hoping to go bigger...would i be able to put 20's on without any major modifications or is 18's the biggest i can go???

can you tell me what your factory tire size is? then i can tell you what size came on the car, then i can figure out what size tire you would need to go with on an 18 or 20 inch rim, and if it is possible...