Determining tire size when increasing wheel dia
So I'm looking for some help here. Once I'm finished with my resoration the last item to get is the wheel. Even though that is quite a ways down the road I like to keep the knowledge handy when the time comes. So here it is, I have the stock wheels and tire size right now which is a 15'' wheel with 4.25 backspace, 5 bolt pattern. Off the top of my head I think the tires are a 225/60/15. I want to go to a 17'' when its all said and done but maintian the overall tire dia and have a smaller sidewall so i dont have to change the speedo gears etc. What tire sizes do you recommend or is there a tool somewhere that you can plug in some numbers and it will tell you? BTW I would like to keep the same tire widths as I am going for a slight rake with 1'' eibach lowering front springs already installed.