Here's a handy tire size/speed calculator: https://tiresize.com/speedometer-calibration/
If you started with 15" tires and went to 17, your speed could be ~7 MPH different.
I went skinnier for better fuel economy.
Everyone jumping my balls after i asked for a honest shop with a little levity thrown in. I guess i should have asked for a dishonest one but thats how i is.
Thanks, i forgot about those shops.