With 4.56’s and 305/40/R22’s (31.6”) I’m turning 2360rpm at 70mph; which really isn’t too bad all things considered and especially since I mainly drive locally.

For comparison purposes, an older F Body with 3.73’s and the stock sized P275/40R17 (25.7”) tires would be turning 2125rpm even with a T-56 or 2375rpm with an automatic. Of course being lighter and having better aerodynamics, it will still result in better economy.

Going with even taller tires, I wouldn’t be scared to jump to 4.56’s at all.

 

I'm getting my 4.56 installed tomorrow. And I'm on a 285/70-17 so I say do it.