245/45/18...The 245 is the width of the tire , but it may not be exactly 245MM every manufacturer is different.
The 45 is your tire side wall height in mm
The 18 is obviously the measurement across the face of the rim
You normally never go wider when using a snow tire . The narrower the tire the less "float" you'll get in snow, but if the price is right and it will fit.....
Last edited by Reznick; 11-23-2012 at 09:52 AM.