There are some good charts online. Google 3.6l pentastar gearing chart. You'll find power curves and rpm ranges at set speeds with tire sizes and etc. There is a good video on YouTube a guy does to compare 3.73's vs. 4.88's shows the rev differences and RPM's. pretty cool. Im going with 4.88's myself because I pull a 3,000# trailer. But like others have said...if the 37'' tire bug bites you you'll be ok with 4.88's. Plus they're generally a little bit cheaper than 4.56's.