For those who don't care to keep the tire diameter even with OE, hit the BACK button.
For everybody else:
Our wagons (or should I say your wagons since I don't have one anymore
) came stock with 225/75r15's. When you buy bigger rims, sizing your tire can be a pain in the arse.
The most common wagon upgrade seems to be the Impala SS rims. The only problem is the stock SS tire, a 255/50r17 is a bit shorter than the OE wagon size. The go to size for years was the 255/55r17. But then everybody stopped making that size.
Well no more. Federal makes it and tires-easy.com stocks them. The price is good, too!
For 18's, The new Camaro's OE 18" size is just about perfect for a wagon. In fact I'll be putting some on a forum member's wagon in a few days. The BF Goodrich Radial T/A Spec in 245/55R18 is available DIRT F'ing CHEAP right now... Cheaper than a 15 inch tire if you look hard enough!
For 20's, I haven't found a cheap size yet... But the DCX SRT cars and the new Camaro run a 245/45r20 that is just about right for a wagon.
If you've found other sizes that are close to stock and don't cost a fortune, POST UP!