Before you "Go with 20s", you should do some tire pricing. Tires larger than 17" get expensive quickly.
If you can get tires with the same circumference (meaning lower aspect ratio),
you should be Ok on fit, but those tires are going to be thin! They will have a punishing ride, and will be very vulnerable to potholes.
yea i understand not going to be the perfect ride but the cars not drove a lot mostly shows and weekends. I know 20s will fit and the tire isn't a problem. All I'm really needing to know is on the offset?