4.56 is an ideal all-around ratio for 33" tires and your 5-speed transmission. Before going to 35" tires and 4.88 gearing, I made the mistake of installing 4.11 gearing for my previous 33" tires. The 4.10 gearing was too high and I had to downshft for even gentle grades. I wish I had listened at that time to all my friends who advised me to go with 4.56. No, 4.56 will not produce excessive highway RPMs, that ratio will just restore the performance that your TJ came with from the factory that was lost due to the bigger tires.