...with the dangblasted 20" tires, but on the test drive they didn't seem that rough or that loud.
I’m not surprised. Your Venza tires actually have more side-wall height than my Insight with stock 15" wheels.
OP here to close the loop.
About a month ago, Craigslist brought together a Venza with 19" wheels and my Venza with 20-inchers. His Venza was red, mine white. His wheels had ten spokes, mine five. My aggressive 5-spoke 20" wheels looked better on his red Venza, and his classic 10-spoke 19" wheels look better on my white Venza.
After the swap, both Venza owners are happy. My Venza seems to ride a little softer, which is what I was after. Not quite a 17" or 18" wheel, but the 19-inchers are starting to grow on me.
Your question sent to Toyota was very simple for them to answer. The only possible answer they can legally give is “NO”. It would be the same with any manufacturer.