Changed to 32" tires (BFG ATs) with my stock 4.10 gears, and using the chart here, determined that I needed a 36 tooth gear:
Bought one, installed it, but now my Jeep appears to read about 5mph over the correct speed at 65mph. I verified this by driving next to a friends car, and by timing between mile markers. So my speedometer reads 70 when I'm going 65mph. I checked a few other online speedometer charts, and they all seem to say 36 teeth for my situation.
I was a little disappointed, as at first I thought the speedometer gear was some magically performance upgrade!
Has anyone else seen this issue? If 36 isn't the right number, what would be? I hate to keep buying gears!