I need to get new rubber for my van. The cost of new tires, plus mounting and balancing, is about the same as purchasing new takeoff wheels for one of these vehicles. The wheels would be 17 inch rims, 5 x 4.50 or 5 x 114.3 bolt pattern, and the tires are 215/65/17. Currently, I have 215/70/15. If I'm doing my math correcty, my speedo will be 7% fast, correct?