I want to get new wheels, but all the nice ones are 18" in size. I don't really care to increase the size of the wheel, but if I want a nice wheel I will have to.

So, currently I have 225/50-17" tires. If I went to 225/45-18" the speedometer would only be 0.4% too slow.

If I were traveling 60 MPH, it would actually be 60.3MPH (big deal, like the speedometer is that acurate to start with).

Does anyone think this size change would impact the handling of the car in a negative way? I take it the 50 and 45 numbers are the height of the tire. So if I changed it from 50 to 45, would the car be lower to the ground? I would assume so, but by less than a half aninch (.23 inches) - from what I gather anyway.

What I really don't understand is if you increase the width of the tire, not the height, it somehow screws with the speedometer... How does the width affect this?

Thanks for any insight, or additional information.

PS - This is for a Mitsubishi Eclipse 2007 GT.

 

okay in a 225/50/r17 the 50 is the aspect ratio. it is a percentage of the measurement from bead lock to bead lock that is in the sidewalls of the tire. theoretically, a 225/50/r17, 225/45/r18, 225/40/r19 etc are the same diameter outside, but they get progressively wider. i went from 225/45/r17 to 225/40/r18 (diameter diff of .1 inch) with no problem. this wont changethe height of the car. expect a little more road noise and a little more feedback to the wheel. tire width will not affect speedo, diameter will. excesively wider tires can cause premature wear on steering components. the change you want to do shouldn't be a problem. hope that helps, i'm going to stop rambling now...

 

when i went from 17 - 18" wheel my speedo was off by about 7mph.

 

i had the same problem.... lol