Found a site with tire calculators on it, converts metric to inches and inches to metric. also has a speedometer calibration calculator to get your actual speed if you go with bigger tires then stock. tire-size-conversion.com
When looking for your next set of Jeep tires there are many things to study. Not only off road performance but on road handling as well. Yeah, we all wish we had one for the week and one for the weekend but that's just not how it works for most of us. We are usually balancing between the two aspects.