that's tire specs. not wheel specs.
re-tires
don't think 50's will fit. 60's require a wheel with a 6" bead width. that's bout as big as you can fit w/o rubbing in back. 60's likely will rub. but only when the tank is full and someone is in the back seat. for that you could easily roll the fender.
re- wheels.
lots to consider,
the problem you're going to have, unless you go through a shop, is finding out the aspects of the oem wheel. need that to calculate/compare to a would be wheel of choice.
this is what you need to know about the oem wheel vs an after market one,
concerns are center hub bore, lug pattern, back spacing, offset, and fender/brake (vehicle equipment) clearance.
here's a tool for calculating plus sizes on vehicles,
http://www.1010tires.com/Packages/
but i still would not be confident untill i checked it out with a retail shop like les schwab.
lookie here,
http://answers.yahoo.com/question/in...3211812AA06iJr
http://answers.yahoo.com/question/in...7222633AAQSdSI