What size tires on new rims

[DDurango]

I am looking at new rims that are 16x8. My stock rims for my Durango are 15x7 with 31 10.5 R15. I was wondering what size tires do I need on the 16x8's to match the exact diameter of the 15x7's with 31 10.5 R15. Also, is it possible to run with 16 or 17 by 9inch on the 4x4 Durango, and if so what would the diameter match be with 31 10.5 R15. I want to run with the same diameter because I don't want to throw off the speedometer, and I have no reason to go with a larger diameter.

[SinCity R/T]

I am looking at new rims that are 16x8. My stock rims for my Durango are 15x7 with 31 10.5 R15. I was wondering what size tires do I need on the 16x8's to match the exact diameter of the 15x7's with 31 10.5 R15.

Here's a good site I use frequently to calculate tire sizes - this way you can tinker with a variety of sizes to find the diameter you want then check with the tire companies to see if they carry any of them.

http://www.rx7turboturbo.com/robrobinette/tire_diameter.htm