Your speedo would be low I would guess around 5mph at normal highway speeds because the 225/45/17's are about an inch and a half bigger in overal circumfurince (sp?) so expect a little drop off. Also depending on the weight of the new rims you could notice a little difference in performance. I could feel the differance when I took my 17" Spiders off and put on the stock rims again it just seemed faster. After I took the car for a spin I weighted the two rims and tires and found there was a 6 lb difference, 49 for the spiders and A520's and 43 for the stock EO and damn near bald GSC's
