The factory size was somewhere around 28". There are speedometer conversion tables all over that will give you an idea of how fast you are going by using RPM, tire size and gear ratio. The circumference of the larger tire is almost 18% more than the stock tires, so your gauge will read about 18% low.
1986 CJ7, 4.2 w/4.0 head, TFI-HEI hybrid ignition, Clifford manifold w/Holley 390 w/cold air intake, OBA, 4.5" lift, Woody CV shaft and Tattons in front, 4.10 gears - lunchbox in front, Truetrac in the back, twin-sticked, blower upgrade for running topless, trying to keep it simple.
It's just a Jeep, and if you don't wheel it once in a while, it's not even that.