I bought Four 255-45-20 Toyo PROXES tires and four 20x8.5 5 lug Brand new CHROME American Eagle 304 wheels off of ebay that should fit. Is there any thing i need to do before putting the rims and tires on. or is there anything i need to do after i put them on such as recalbrate the speedo thanks for any help given

 

You will need to tell the PCM about the size change. If you have a SuperChips programmer it will do it... if not a dealership should do this for you.

 

I have the same size setup as that and according to the Les Schwab people it is the same overall diameter as the factory 18's.
No recalibrating or updating was needed.

 

Thanks Magmania, you are right.

Obviously I'm wheel challenged here Here's a good resource for those that are challenged like me online tire size calculator from Discount Tire.