Originally Posted by trev762
Yes if u r comparing same width (245/45/17 vs 245/40/18) but if u compare 225/45/17 vs 245/40/18 the 225/45/17 will have a smaller diameter due to the shorter width u need to remember the wider the tire the taller the tire will be with the same series but varies from brand of tire.
My dedicated winter tires r blizzak lm60 225/45/17 vs my 245/40/18. Since I have the performance winter tires and even though they're a 45 series r a smaller diameter by about 1" giving more wheel well clearance.
so, you're getting more clearance because you are going to a shorter overall tire diameter (as well as narrower). it has nothing to do with being on a 17 vs. 18, which is what you claimed, and could be very confusing to someone who doesn't understand how this works. I am trying to make it as clear as possible for the OP here. he could just as easily have decided that 225/50R17 was the right size because it is closer in overall diameter than a 225/45R17, especially if he doesn't want to lose 0.38" in ride height. and that 0.38" is also the amount of extra clearance you have above, although the narrower tire helps you get in there at an angle.
let's be clear here for the people that don't understand how it all works.