265/65r18 tires will give you the same overall diameter as 265/70r17, roughly 31.6 inches.
You're right about tires for the 18" wheels. There are less options, and they're often more expensive.
If you really like your 18" wheels, there are AT tired in the 265/65r18 size. If you don't mind changing, it may not be that much more expensive to get some 17" wheels so you have more options.
1995 Wrangler Rio Grande: RE 4.5" Lift, 33" MT/R's
2010 Grand Cherokee Limited: Hemi, QD II, 30" Nitto Terra Grapplers